The Calendar hole will go live in approximately 12 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 561st ovs-code 🇩🇪 887 73 340ms 22 Jul 2023 562nd albanian-laundromat 887 94 415ms 24 Sep 2025 562nd jkelly467 887 94 544ms 23 Oct 2025 562nd HumanoidCPU 887 94 397ms 8 Nov 2025 565th snoozingnewt 🇨🇦 887 96 109ms 15 days ago 566th GolfingSuccess 🇬🇷 886 71 2ms 5 May 2022 566th emplv 🇱🇻 886 71 2ms 5 May 2022 566th JayXon 🇺🇸 886 71 2ms 7 May 2022 566th nwellnhof 🇩🇪 886 71 2ms 5 Jun 2022 566th stefangimmillaro 886 71 2ms 2 Jun 2023 566th 09cf 886 71 7ms 4 Oct 2023 566th kkoenig 886 71 2ms 21 Dec 2023 566th sean-niemann 🇺🇸 886 71 2ms 10 Jul 2024 566th masinag 🇮🇹 886 71 2ms 6 Oct 2024 575th janbehrens 🇩🇪 886 90 442ms 21 Apr 2023 575th Yewzir 🇧🇪 886 90 426ms 22 Apr 2023 575th DialFrost 🇸🇬 886 90 440ms 6 Nov 2023 575th Ripick 886 90 439ms 27 Nov 2024 575th emgordon154 886 90 368ms 9 days ago 580th m-tkach 🇺🇦 886 112 118ms 22 Jun 2025 581st steffan-polygolf 885 74 136ms 14 Feb 2024 581st prestosilver 🇺🇸 885 74 124ms 30 hours ago 583rd SiestaGuru 885 88 326ms 9 Jan 2023 583rd rifatx 885 88 322ms 5 Jul 2024 583rd kmathis22 885 88 367ms 25 Sep 2025 583rd arcpolaris 885 88 391ms 8 Nov 2025 587th m-tkach 🇺🇦 884 59 404ms 21 Jan 2024 587th GolfingSuccess 🇬🇷 884 59 474ms 20 Jan 2025 587th duckyluuk 🇳🇱 884 59 450ms 15 days ago 590th kg583 🇺🇸 884 84 18ms 30 Jul 2025 591st nipzu 884 94 116ms 17 May 2022 591st Natanaelel 🇸🇪 884 94 125ms 17 Jun 2022 591st nkoppel 884 94 120ms 19 Oct 2022 591st ovs-code 🇩🇪 884 94 120ms 21 Jun 2023 591st mousetail 🇳🇱 884 94 124ms 12 Jan 2024 596th sean-niemann 🇺🇸 884 109 274ms 25 May 2024 596th GolfingSuccess 🇬🇷 884 109 273ms 6 Sep 2025 598th MichalMarsalek 🇨🇿 883 70 19ms 5 May 2022 598th primo-ppcg 🇹🇭 883 70 23ms 5 May 2022 598th SirBogman 🇺🇸 883 70 19ms 5 May 2022 598th prplz 🇦🇺 883 70 18ms 5 May 2022 598th Irratix 🇳🇱 883 70 18ms 7 May 2022 598th rak1507 🇬🇧 883 70 19ms 7 May 2022 598th inventshah 883 70 17ms 9 May 2022 598th k3w1k0d3r 883 70 18ms 22 Jun 2022 598th ZakkkkAttackkkk 🇵🇭 883 70 17ms 14 Jul 2022 598th Bonjour27891 🇻🇳 883 70 20ms 14 Jul 2022 598th OllieBoyne 🇬🇧 883 70 18ms 19 Jul 2022 598th wen1now 883 70 19ms 8 Aug 2022 598th 051 🇸🇬 883 70 18ms 8 Aug 2022 598th Sp3000 🇦🇺 883 70 19ms 8 Aug 2022 598th betaveros 883 70 19ms 9 Aug 2022 598th shelerr 883 70 18ms 9 Sep 2022 598th stewSquared 🇺🇸 883 70 22ms 27 Sep 2022 598th orthoplex 🇨🇽 883 70 23ms 9 Oct 2022 598th 5quiwyrm 883 70 17ms 19 Oct 2022 598th myfatemi04 883 70 19ms 4 Nov 2022 598th kevinmchung 883 70 18ms 4 Nov 2022 598th FlorianCassayre 🇫🇷 883 70 18ms 7 Nov 2022 598th fourth-bit 883 70 18ms 29 Nov 2022 598th QuincyNash 🇺🇸 883 70 18ms 29 Nov 2022 598th aksyristos 883 70 18ms 25 Dec 2022 598th thizanne 883 70 20ms 27 Dec 2022 598th Alex-x90 🇺🇸 883 70 21ms 20 Jan 2023 598th bob-th 883 70 18ms 24 Jan 2023 598th SirFireball3521 883 70 17ms 25 Jan 2023 598th stefangimmillaro 883 70 19ms 6 Feb 2023 598th Seek64 🇩🇪 883 70 18ms 7 Feb 2023 598th FieryIceStickie 883 70 19ms 3 Apr 2023 598th MeWhenI 🇻🇦 883 70 19ms 30 Apr 2023 598th fgrosshans 🇫🇷 883 70 18ms 5 May 2023 598th Shanethegamer 🇺🇸 883 70 21ms 25 May 2023 598th InigoK 🇺🇸 883 70 19ms 14 Jun 2023 598th quimey 883 70 15ms 15 Jun 2023 598th CornerMercury 🇬🇧 883 70 19ms 19 Jun 2023 598th ndren 883 70 20ms 2 Aug 2023 598th janbehrens 🇩🇪 883 70 19ms 24 Nov 2023 598th namelessiw 883 70 20ms 9 Jan 2024 598th mathisfun271 883 70 18ms 13 Feb 2024 598th Just4FunCoder 883 70 20ms 17 Feb 2024 First Prev 561–640 of 3,526 Next Last