The Calendar hole will go live in approximately 2 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 399th revlayle 🇺🇸 903 86 337ms 7 Dec 2022 399th albanian-laundromat 903 86 379ms 30 Sep 2025 403rd Betuaredead 902 60 5ms 5 Jan 2023 403rd Yewzir 🇧🇪 902 60 5ms 12 Feb 2023 403rd Steffan153 🇫🇮 902 60 5ms 23 Feb 2023 403rd GolfingSuccess 🇬🇷 902 60 5ms 16 Oct 2024 403rd sean-niemann 🇺🇸 902 60 9ms 7 Mar 2025 408th edsrzf 🇳🇿 902 83 43ms 14 Jan 2025 408th kg583 🇺🇸 902 83 42ms 14 Feb 2025 410th m-tkach 🇺🇦 902 90 30ms 7 Dec 2023 411th shellbertt 🇨🇦 901 62 19ms 4 May 2022 411th ZakkkkAttackkkk 🇵🇭 901 62 19ms 5 May 2022 411th annaproxy 901 62 19ms 8 Jun 2022 411th bob-th 901 62 24ms 9 Jul 2022 411th btjones0 901 62 23ms 15 Jul 2022 411th tri1212 🇻🇳 901 62 19ms 18 Jul 2022 411th fredrik-bakke 🇳🇴 901 62 23ms 5 Oct 2022 411th jakobkordez 🇸🇮 901 62 19ms 19 Oct 2022 411th Fishron 901 62 19ms 29 Nov 2022 411th KatieLG 🇬🇧 901 62 22ms 11 Dec 2022 411th ItsMeNoobieboy 901 62 20ms 20 Dec 2022 411th firegene 🇮🇪 901 62 19ms 3 Jan 2023 411th ljweel 901 62 19ms 13 Feb 2023 411th 2011-Chan-Ethan 901 62 18ms 9 Jul 2023 411th elgan65536 901 62 19ms 18 Nov 2023 411th Dataen 901 62 19ms 16 Jan 2024 411th Yewzir 🇧🇪 901 62 49ms 5 Apr 2024 411th cuboids 901 62 20ms 11 Jul 2024 411th wuzekai518 901 62 24ms 26 Jul 2024 411th abhishekg999 901 62 49ms 17 Sep 2024 411th lifthrasiir 🇰🇷 901 62 19ms 16 Nov 2024 411th Artemis21 🇬🇧 901 62 19ms 17 Jan 2025 411th lolgeny 901 62 19ms 22 Feb 2025 411th keelimeguy 🇺🇸 901 62 19ms 15 May 2025 411th Flekay 🇩🇪 901 62 19ms 19 Jun 2025 411th DoubleUynn 901 62 19ms 25 Jun 2025 411th JOrE20 🇺🇸 901 62 17ms 22 Nov 2025 438th GolfingSuccess 🇬🇷 901 64 91ms 14 Dec 2024 438th MeWhenI 🇻🇦 901 64 91ms 24 Dec 2024 438th GrayJoKing 🇦🇺 901 64 92ms 25 Nov 2025 441st kg583 🇺🇸 901 79 24ms 30 Jul 2025 442nd Lydxn 🇨🇦 900 64 181ms 1 Apr 2023 443rd sean-niemann 🇺🇸 900 75 5ms 5 days ago 444th Kacarott 🇦🇺 900 79 117ms 13 Jun 2024 445th stefangimmillaro 900 92 131ms 24 Oct 2023 445th inverseLorentz 🇦🇺 900 92 128ms 27 May 2024 445th sean-niemann 🇺🇸 900 92 125ms 8 Jun 2025 445th ian-h-chamberlain 🇺🇸 900 92 123ms 23 Nov 2025 449th michael-pruglo 🇺🇦 900 94 57ms 5 Jul 2022 449th zygoloid 900 94 56ms 5 Aug 2024 449th AdrienHache 🇫🇷 900 94 60ms 37 hours ago 452nd shinh 899 52 39ms 29 Jun 2022 452nd MeWhenI 🇻🇦 899 52 69ms 25 Jul 2023 454th MeWhenI 🇻🇦 899 63 184ms 5 May 2022 455th Lydxn 🇨🇦 898 70 91ms 7 May 2022 456th MeWhenI 🇻🇦 898 71 102ms 20 Aug 2024 457th m-tkach 🇺🇦 898 72 99ms 16 Oct 2022 457th GrayJoKing 🇦🇺 898 72 105ms 22 Oct 2022 457th emplv 🇱🇻 898 72 101ms 27 Oct 2022 457th sean-niemann 🇺🇸 898 72 117ms 7 Mar 2025 461st Steffan153 🇫🇮 898 82 42ms 1 Apr 2023 461st sean-niemann 🇺🇸 898 82 42ms 12 Jul 2024 463rd albanian-laundromat 897 106 267ms 6 days ago 464th Lydxn 🇨🇦 895 69 7ms 12 Sep 2022 464th GrayJoKing 🇦🇺 895 69 7ms 12 Sep 2022 464th btnlq 895 69 7ms 24 Sep 2022 464th trinityy-7 895 69 2ms 7 Aug 2025 468th Steffan153 🇫🇮 893 67 113ms 18 Dec 2022 468th Lydxn 🇨🇦 893 67 116ms 4 Feb 2023 468th DialFrost 🇸🇬 893 67 99ms 17 Mar 2025 471st SirBogman 🇺🇸 892 50 402ms 5 May 2022 471st nwellnhof 🇩🇪 892 50 397ms 3 Jun 2022 471st Lydxn 🇨🇦 892 50 404ms 15 Aug 2022 471st Steffan153 🇫🇮 892 50 408ms 9 Aug 2024 475th Lydxn 🇨🇦 892 72 353ms 16 Jul 2023 476th edsrzf 🇳🇿 892 78 11ms 26 Oct 2024 476th kg583 🇺🇸 892 78 12ms 25 Sep 2025 478th MichalMarsalek 🇨🇿 892 87 366ms 5 May 2022 478th Kloppermand 🇩🇰 892 87 375ms 7 Oct 2022 478th bwat2 892 87 339ms 6 Apr 2023 First Prev 401–480 of 3,488 Next Last