The Calendar hole will go live in approximately 34 hours. Why not try and solve it ahead of time?
Collatz in all languages in chars. Achievements Cheevos Holes Languages Medals Miscellaneous All Holes 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Apéry’s Constant Binary Lambda Calculus Calendar Connect Four Continued Fractions Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers Multitap Input NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial All Languages ><> Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig 05AB1E ALGOL 68 APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Bytes Chars Scoring Bytes Chars Language All ><> Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig Experimental Language 05AB1E ALGOL 68 APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Hole All 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Experimental Hole Apéry’s Constant Binary Lambda Calculus Calendar Connect Four Continued Fractions Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers Multitap Input NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial # Golfer Points Chars Time Submitted 800th Schmitt-Very-Cool 857 97 435ms 26 Sep 2025 802nd typeswitch-dev 🇵🇹 856 75 5ms 22 Jul 2023 803rd ovs-code 🇩🇪 856 83 54ms 1 Jul 2024 804th 386asm 🇺🇸 856 86 40ms 9 Apr 2023 804th DialFrost 🇸🇬 856 86 43ms 7 hours ago 806th nwellnhof 🇩🇪 856 111 271ms 4 May 2022 806th stefangimmillaro 856 111 268ms 26 Sep 2023 806th kkoenig 856 111 287ms 4 Jan 2024 809th frankgraziano 856 198 108ms 14 Oct 2025 810th Frowny 855 38 40ms 5 May 2022 810th stackofbears 855 38 42ms 14 Mar 2025 812th dokutan 855 79 11ms 27 Apr 2024 813th DialFrost 🇸🇬 854 50 253ms 24 Oct 2023 814th Shanethegamer 🇺🇸 854 70 99ms 12 Dec 2022 814th Alessandro-Balconi 🇮🇹 854 70 95ms 26 Dec 2022 814th snoozingnewt 🇨🇦 854 70 207ms 22 Nov 2025 817th henrydukepickle 854 97 118ms 8 Jul 2025 818th yeminghan2021 854 99 66ms 3 Feb 2025 819th aditsu 853 77 3,141ms 23 Nov 2025 820th eshilo-draper 853 91 365ms 4 Sep 2022 820th ericlangedijk 🇸🇮 853 91 389ms 23 May 2023 820th KatieLG 🇬🇧 853 91 363ms 30 Apr 2024 820th Mikey-Beep 🇬🇧 853 91 341ms 3 Sep 2024 824th ovs-code 🇩🇪 853 161 1,719ms 14 Sep 2025 825th Shanethegamer 🇺🇸 852 83 1,354ms 4 May 2022 826th MeWhenI 🇻🇦 852 92 398ms 10 Oct 2022 826th Betuaredead 852 92 468ms 5 Jan 2023 826th Yax42 🇫🇷 852 92 420ms 4 Oct 2025 829th o0lit3 🇺🇸 851 54 7ms 22 Jun 2023 829th Natanaelel 🇸🇪 851 54 7ms 10 Feb 2025 831st Shanethegamer 🇺🇸 851 58 767ms 17 Sep 2025 832nd Yewzir 🇧🇪 851 65 4ms 9 Oct 2023 832nd MeWhenI 🇻🇦 851 65 3ms 10 Oct 2023 834th SirBogman 🇺🇸 850 55 41ms 5 May 2022 834th olivermrose 🇺🇸 850 55 45ms 6 May 2022 834th 4hg 🇺🇸 850 55 43ms 24 Aug 2022 834th DialFrost 🇸🇬 850 55 45ms 1 Jan 2023 834th error256 850 55 40ms 4 May 2024 839th mtirado1 850 74 83ms 24 Dec 2022 839th Betuaredead 850 74 81ms 6 Jan 2023 839th KatieLG 🇬🇧 850 74 81ms 15 Jan 2023 839th bwat2 850 74 84ms 31 Mar 2023 839th stackotter 850 74 82ms 29 May 2023 839th ovs-code 🇩🇪 850 74 82ms 17 Apr 2024 839th madeforlosers 850 74 80ms 21 Nov 2024 846th Shanethegamer 🇺🇸 850 99 24ms 27 Apr 2023 847th JayXon 🇺🇸 848 56 998ms 9 May 2022 848th DialFrost 🇸🇬 848 162 1,753ms 13 Sep 2025 849th the-zammers 847 68 172ms 2 Oct 2023 850th MeWhenI 🇻🇦 846 26 163ms 25 Aug 2022 850th AlephSquirrel 846 26 209ms 6 Jan 2023 850th ovs-code 🇩🇪 846 26 378ms 5 May 2024 850th saito-ta 🇯🇵 846 26 156ms 12 Dec 2024 854th randolchance 846 63 11ms 8 Jan 2023 854th CatsAreFluffy 846 63 10ms 18 Feb 2023 854th amiralitaheri 846 63 10ms 23 Feb 2023 854th RuyiLi 846 63 9ms 1 Apr 2023 854th TaserTheFox 🇺🇸 846 63 10ms 25 May 2023 854th pfysches-boop 846 63 9ms 6 Aug 2023 854th mhgockel 846 63 10ms 19 Aug 2023 854th NickTheEASDude 🇺🇸 846 63 10ms 18 Jan 2024 854th 823126 846 63 14ms 14 Nov 2024 854th Palladium02 846 63 9ms 12 May 2025 854th 4very 846 63 10ms 10 Jun 2025 854th Ultra814 846 63 9ms 21 Aug 2025 866th NewDefectus 🇮🇱 846 73 3ms 6 May 2022 866th inventshah 846 73 2ms 12 Jun 2022 866th Natanaelel 🇸🇪 846 73 3ms 15 Jun 2022 866th Herbert00709 🇵🇱 846 73 2ms 22 Dec 2023 866th LorenzoDeGaspari 846 73 2ms 27 May 2024 866th Bpc-CPU 846 73 2ms 12 Jul 2025 866th AZTECCO 846 73 2ms 16 Sep 2025 866th CaedenHarper 🇨🇦 846 73 2ms 28 Sep 2025 866th prestosilver 🇺🇸 846 73 2ms 26 days ago 875th jared-hughes 846 100 63ms 20 Jul 2022 875th ZakkkkAttackkkk 🇵🇭 846 100 64ms 10 Aug 2022 875th Walter225 846 100 63ms 25 Jul 2023 878th Natanaelel 🇸🇪 845 57 417ms 17 Jan 2024 878th Kacarott 🇦🇺 845 57 394ms 10 Sep 2024 878th albanian-laundromat 845 57 494ms 7 Oct 2025 First Prev 801–880 of 3,489 Next Last