The Calendar hole will go live in approximately 8 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 401st MeWhenI 🇻🇦 905 71 102ms 20 Aug 2024 402nd m-tkach 🇺🇦 904 72 99ms 16 Oct 2022 402nd GrayJoKing 🇦🇺 904 72 105ms 22 Oct 2022 402nd emplv 🇱🇻 904 72 101ms 27 Oct 2022 402nd sean-niemann 🇺🇸 904 72 117ms 7 Mar 2025 406th Steffan153 🇫🇮 904 82 42ms 1 Apr 2023 406th sean-niemann 🇺🇸 904 82 42ms 12 Jul 2024 408th stefangimmillaro 904 92 131ms 24 Oct 2023 408th inverseLorentz 🇦🇺 904 92 128ms 27 May 2024 408th sean-niemann 🇺🇸 904 92 125ms 8 Jun 2025 408th ian-h-chamberlain 🇺🇸 904 92 123ms 23 Nov 2025 412th Lydxn 🇨🇦 902 69 7ms 12 Sep 2022 412th GrayJoKing 🇦🇺 902 69 7ms 12 Sep 2022 412th btnlq 902 69 7ms 24 Sep 2022 415th sean-niemann 🇺🇸 902 75 5ms 4 hours ago 416th michael-pruglo 🇺🇦 902 94 64ms 5 Jul 2022 416th zygoloid 902 94 74ms 5 Aug 2024 418th albanian-laundromat 901 107 368ms 19 hours ago 419th SirBogman 🇺🇸 900 50 402ms 5 May 2022 419th nwellnhof 🇩🇪 900 50 397ms 3 Jun 2022 419th Lydxn 🇨🇦 900 50 404ms 15 Aug 2022 419th Steffan153 🇫🇮 900 50 408ms 9 Aug 2024 423rd Steffan153 🇫🇮 900 67 113ms 18 Dec 2022 423rd Lydxn 🇨🇦 900 67 116ms 4 Feb 2023 423rd sean-niemann 🇺🇸 900 67 103ms 7 Mar 2025 426th Lydxn 🇨🇦 900 72 353ms 16 Jul 2023 427th Lydxn 🇨🇦 898 48 303ms 5 May 2022 427th p-zubieta 898 48 316ms 6 Mar 2024 429th GrayJoKing 🇦🇺 898 70 3ms 6 May 2022 429th saito-ta 🇯🇵 898 70 2ms 21 Dec 2023 429th ovs-code 🇩🇪 898 70 2ms 17 Feb 2024 429th trinityy-7 898 70 2ms 7 Aug 2025 429th KasperKivimaeki 🇫🇮 898 70 6ms 8 Aug 2025 434th edsrzf 🇳🇿 898 78 11ms 26 Oct 2024 434th kg583 🇺🇸 898 78 12ms 25 Sep 2025 436th GrayJoKing 🇦🇺 898 91 29ms 19 Jan 2023 437th DialFrost 🇸🇬 897 29 218ms 15 Mar 2025 438th Steffan153 🇫🇮 897 59 131ms 10 Aug 2024 438th rucin93 🇵🇱 897 59 132ms 13 Oct 2024 438th sean-niemann 🇺🇸 897 59 134ms 13 Oct 2024 438th lukegustafson 🇺🇸 897 59 133ms 24 Oct 2024 442nd Ripick 897 73 133ms 8 May 2023 443rd nwellnhof 🇩🇪 896 69 22ms 4 May 2022 443rd m-tkach 🇺🇦 896 69 17ms 4 May 2022 443rd GolfingSuccess 🇬🇷 896 69 15ms 5 May 2022 443rd jared-hughes 896 69 17ms 5 May 2022 443rd ovs-code 🇩🇪 896 69 23ms 5 May 2022 443rd btnlq 896 69 17ms 5 May 2022 443rd sisyphus-ppcg 🇦🇺 896 69 14ms 6 May 2022 443rd lynn 896 69 16ms 22 Aug 2022 443rd Steffan153 🇫🇮 896 69 17ms 15 Nov 2022 443rd AlexanderFair 896 69 23ms 19 Jul 2023 443rd pardouin 🇫🇷 896 69 17ms 11 Nov 2023 443rd AlephSquirrel 896 69 478ms 30 Dec 2023 443rd kg583 🇺🇸 896 69 23ms 28 Jan 2024 443rd davecame 896 69 22ms 20 Aug 2024 443rd zacjl 896 69 17ms 19 Sep 2024 443rd starfihs 896 69 16ms 12 Oct 2024 443rd kops-cg 896 69 22ms 9 Feb 2025 443rd sean-niemann 🇺🇸 896 69 17ms 7 Mar 2025 443rd plcc0 896 69 15ms 26 Mar 2025 443rd yujh-yujh 🇬🇸 896 69 16ms 28 Mar 2025 443rd moustave 896 69 16ms 10 Jun 2025 443rd 4atj 896 69 3,539ms 30 Jun 2025 443rd dirckvdende 896 69 18ms 11 Jul 2025 443rd xnor-gate 896 69 16ms 19 Aug 2025 443rd BrunoVisnadi 🇧🇷 896 69 16ms 1 Oct 2025 443rd Mukundan314 896 69 18ms 13 Nov 2025 443rd bizy-coder 896 69 16ms 21 Nov 2025 443rd duckyluuk 🇳🇱 896 69 17ms 18 days ago 443rd bricknellj 896 69 17ms 18 days ago 472nd ovs-code 🇩🇪 896 89 438ms 24 Jul 2024 472nd jipsong 🇩🇪 896 89 467ms 7 Apr 2025 474th MichalMarsalek 🇨🇿 895 87 366ms 5 May 2022 474th Kloppermand 🇩🇰 895 87 375ms 7 Oct 2022 474th bwat2 895 87 348ms 6 Apr 2023 477th Shanethegamer 🇺🇸 894 61 5ms 31 Oct 2022 477th MeWhenI 🇻🇦 894 61 5ms 4 Nov 2022 479th JayXon 🇺🇸 894 74 4,173ms 14 Nov 2024 480th oeb25 894 93 120ms 16 May 2022 First Prev 401–480 of 3,499 Next Last