The Calendar hole will go live in approximately 11 days. Why not try and solve it ahead of time?
Collatz in all languages in bytes. 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 Bytes Time Submitted 799th HumanoidCPU 868 73 81ms 7 May 2024 802nd mtirado1 868 75 7ms 13 Aug 2022 803rd nwellnhof 🇩🇪 868 111 271ms 4 May 2022 803rd emplv 🇱🇻 868 111 296ms 5 May 2022 803rd Shanethegamer 🇺🇸 868 111 261ms 21 Nov 2023 806th pardouin 🇫🇷 867 61 129ms 7 Aug 2024 807th MeWhenI 🇻🇦 867 92 398ms 10 Oct 2022 807th Betuaredead 867 92 468ms 5 Jan 2023 807th Yax42 🇫🇷 867 92 420ms 4 Oct 2025 810th bac0id 866 90 336ms 26 Sep 2023 810th deadp4nda 🇩🇪 866 90 372ms 26 Apr 2024 810th 123mjb 866 90 352ms 23 Jun 2025 810th michelebastione 🇮🇹 866 90 384ms 24 Aug 2025 810th razvandmtr 🇷🇴 866 90 385ms 6 Nov 2025 810th amazingalek 866 90 429ms 4 hours ago 816th TylerBloom 866 96 115ms 22 Mar 2024 817th 5quiwyrm 865 52 300ms 4 Sep 2022 817th MeWhenI 🇻🇦 865 52 280ms 28 Jan 2023 817th Feniske 🇫🇷 865 52 280ms 7 Nov 2023 817th dcgjb 865 52 297ms 29 Jan 2024 817th JPRuskin 🇬🇧 865 52 313ms 7 Apr 2025 817th IISResetMe 865 52 267ms 7 Apr 2025 817th Ripick 865 52 266ms 1 Jun 2025 824th Andriamanitra 🇫🇮 865 67 144ms 26 Apr 2023 825th MeWhenI 🇻🇦 865 81 8ms 23 May 2023 826th shellbertt 🇨🇦 865 98 66ms 9 May 2022 826th iakolzin 865 98 85ms 26 May 2022 826th Betuaredead 865 98 78ms 5 Jan 2023 826th oceko 865 98 73ms 19 Feb 2024 826th dokutan 865 98 81ms 17 Mar 2024 826th cuzdav 865 98 62ms 4 May 2025 826th timhaj 🇸🇮 865 98 82ms 12 Sep 2025 826th Yax42 🇫🇷 865 98 75ms 4 Oct 2025 834th typeswitch-dev 🇵🇹 864 75 5ms 22 Jul 2023 835th DialFrost 🇸🇬 864 86 18ms 15 Dec 2024 836th Setvizan 863 62 10ms 12 Jan 2023 836th GreenBeansAgainstVeganism 863 62 10ms 13 Jan 2023 836th arctouch-cristiannevianna 863 62 10ms 3 Apr 2023 836th Corxldyphik 863 62 10ms 11 Apr 2023 836th Blockyheadman 863 62 10ms 1 Nov 2023 836th ollyspooner 863 62 10ms 22 Nov 2023 836th itserasmus 863 62 10ms 25 Jan 2024 836th Jacob385 863 62 10ms 13 Mar 2024 836th junkondo-jp 863 62 11ms 30 Jun 2024 836th ShiraJoseph 🇺🇸 863 62 9ms 1 Mar 2025 836th tomh1012 863 62 9ms 17 days ago 847th MeWhenI 🇻🇦 863 145 526ms 28 Mar 2025 848th HPWiz 🇳🇿 862 50 346ms 4 May 2022 848th JayXon 🇺🇸 862 50 313ms 5 May 2022 848th Steffan153 🇫🇮 862 50 287ms 10 Dec 2022 848th ovs-code 🇩🇪 862 50 418ms 24 Oct 2023 848th sean-niemann 🇺🇸 862 50 344ms 12 Jul 2024 853rd 386asm 🇺🇸 862 86 40ms 9 Apr 2023 854th ovs-code 🇩🇪 862 161 1,719ms 14 Sep 2025 854th Yewzir 🇧🇪 862 161 2,399ms 14 Nov 2025 856th Shanethegamer 🇺🇸 861 58 767ms 17 Sep 2025 857th Shanethegamer 🇺🇸 861 70 99ms 12 Dec 2022 857th Alessandro-Balconi 🇮🇹 861 70 95ms 26 Dec 2022 859th NewDefectus 🇮🇱 861 73 3ms 6 May 2022 859th Natanaelel 🇸🇪 861 73 3ms 15 Jun 2022 859th LorenzoDeGaspari 861 73 2ms 27 May 2024 859th Bpc-CPU 861 73 2ms 12 Jul 2025 859th AZTECCO 861 73 2ms 16 Sep 2025 859th CaedenHarper 🇨🇦 861 73 2ms 28 Sep 2025 859th prestosilver 🇺🇸 861 73 2ms 17 days ago 866th Liibe 860 97 391ms 25 Sep 2025 867th stefangimmillaro 860 112 268ms 26 Sep 2023 867th kkoenig 860 112 287ms 4 Jan 2024 869th o0lit3 🇺🇸 859 54 7ms 22 Jun 2023 869th Natanaelel 🇸🇪 859 54 7ms 10 Feb 2025 871st scpchicken 🇵🇼 859 72 19ms 4 May 2022 871st sultan 859 72 17ms 6 Jun 2022 871st annaproxy 859 72 20ms 22 Aug 2022 871st BlankSpruce 859 72 23ms 9 Sep 2022 871st ValentinCassayre 859 72 21ms 8 Oct 2022 871st mathb0y512 859 72 21ms 1 Dec 2022 871st NoahBolohan 🇨🇦 859 72 21ms 28 Feb 2023 871st neel11235813 859 72 21ms 8 Mar 2023 871st Kacarott 🇦🇺 859 72 16ms 24 Mar 2023 871st Fracture17 859 72 20ms 8 Apr 2023 First Prev 801–880 of 3,529 Next Last