The Calendar hole will go live in approximately 11 days. 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 794th TeodorDyakov 🇧🇬 857 72 3ms 8 Jul 2025 794th xiaoyiming123 857 72 2ms 12 Jul 2025 803rd Liibe 857 97 391ms 25 Sep 2025 803rd Schmitt-Very-Cool 857 97 435ms 26 Sep 2025 805th typeswitch-dev 🇵🇹 856 75 5ms 22 Jul 2023 806th ovs-code 🇩🇪 856 83 54ms 1 Jul 2024 807th 386asm 🇺🇸 856 86 40ms 9 Apr 2023 808th nwellnhof 🇩🇪 856 111 271ms 4 May 2022 808th stefangimmillaro 856 111 268ms 26 Sep 2023 808th kkoenig 856 111 287ms 4 Jan 2024 811th frankgraziano 856 198 113ms 14 Oct 2025 812th Frowny 855 38 40ms 5 May 2022 812th stackofbears 855 38 42ms 14 Mar 2025 814th DialFrost 🇸🇬 854 50 309ms 24 Oct 2023 815th Shanethegamer 🇺🇸 854 70 99ms 12 Dec 2022 815th Alessandro-Balconi 🇮🇹 854 70 95ms 26 Dec 2022 815th snoozingnewt 🇨🇦 854 70 207ms 22 Nov 2025 818th henrydukepickle 854 97 118ms 8 Jul 2025 819th yeminghan2021 854 99 86ms 3 Feb 2025 820th aditsu 853 77 3,684ms 27 days ago 821st eshilo-draper 853 91 365ms 4 Sep 2022 821st ericlangedijk 🇸🇮 853 91 389ms 23 May 2023 821st KatieLG 🇬🇧 853 91 382ms 30 Apr 2024 821st Mikey-Beep 🇬🇧 853 91 341ms 3 Sep 2024 825th ovs-code 🇩🇪 853 161 1,719ms 14 Sep 2025 826th frosster 852 76 7ms 12 May 2023 826th kyleclaassen 852 76 7ms 20 May 2023 826th NickTheEASDude 🇺🇸 852 76 6ms 7 May 2024 826th koipondx86 852 76 7ms 8 Nov 2024 830th Shanethegamer 🇺🇸 852 83 1,354ms 4 May 2022 831st MeWhenI 🇻🇦 852 92 398ms 10 Oct 2022 831st Betuaredead 852 92 468ms 5 Jan 2023 831st Yax42 🇫🇷 852 92 420ms 4 Oct 2025 834th o0lit3 🇺🇸 851 54 7ms 22 Jun 2023 834th Natanaelel 🇸🇪 851 54 7ms 10 Feb 2025 836th Shanethegamer 🇺🇸 851 58 767ms 17 Sep 2025 837th Yewzir 🇧🇪 851 65 4ms 9 Oct 2023 837th MeWhenI 🇻🇦 851 65 3ms 10 Oct 2023 839th SirBogman 🇺🇸 850 55 36ms 5 May 2022 839th olivermrose 🇺🇸 850 55 38ms 6 May 2022 839th 4hg 🇺🇸 850 55 59ms 24 Aug 2022 839th DialFrost 🇸🇬 850 55 42ms 1 Jan 2023 839th error256 850 55 44ms 4 May 2024 844th mtirado1 850 74 83ms 24 Dec 2022 844th Betuaredead 850 74 81ms 6 Jan 2023 844th KatieLG 🇬🇧 850 74 81ms 15 Jan 2023 844th bwat2 850 74 84ms 31 Mar 2023 844th stackotter 850 74 82ms 29 May 2023 844th ovs-code 🇩🇪 850 74 82ms 17 Apr 2024 844th madeforlosers 850 74 80ms 21 Nov 2024 851st Shanethegamer 🇺🇸 850 99 24ms 27 Apr 2023 852nd albanian-laundromat 849 112 254ms 17 days ago 853rd JayXon 🇺🇸 848 56 998ms 9 May 2022 854th DialFrost 🇸🇬 848 162 1,753ms 13 Sep 2025 854th emgordon154 848 162 1,669ms 17 Sep 2025 856th the-zammers 847 68 172ms 2 Oct 2023 857th MeWhenI 🇻🇦 846 26 275ms 25 Aug 2022 857th AlephSquirrel 846 26 149ms 6 Jan 2023 857th ovs-code 🇩🇪 846 26 576ms 5 May 2024 857th saito-ta 🇯🇵 846 26 194ms 12 Dec 2024 861st randolchance 846 63 11ms 8 Jan 2023 861st CatsAreFluffy 846 63 10ms 18 Feb 2023 861st amiralitaheri 846 63 10ms 23 Feb 2023 861st RuyiLi 846 63 9ms 1 Apr 2023 861st TaserTheFox 🇺🇸 846 63 10ms 25 May 2023 861st pfysches-boop 846 63 9ms 6 Aug 2023 861st mhgockel 846 63 10ms 19 Aug 2023 861st NickTheEASDude 🇺🇸 846 63 10ms 18 Jan 2024 861st 823126 846 63 14ms 14 Nov 2024 861st Palladium02 846 63 9ms 12 May 2025 861st 4very 846 63 10ms 10 Jun 2025 861st Ultra814 846 63 9ms 21 Aug 2025 873rd NewDefectus 🇮🇱 846 73 3ms 6 May 2022 873rd inventshah 846 73 2ms 12 Jun 2022 873rd Natanaelel 🇸🇪 846 73 3ms 15 Jun 2022 873rd Herbert00709 🇵🇱 846 73 2ms 22 Dec 2023 873rd LorenzoDeGaspari 846 73 2ms 27 May 2024 873rd Bpc-CPU 846 73 2ms 12 Jul 2025 873rd AZTECCO 846 73 2ms 16 Sep 2025 873rd CaedenHarper 🇨🇦 846 73 2ms 28 Sep 2025 First Prev 801–880 of 3,505 Next Last