The Calendar hole will go live in approximately 17 hours. Why not try and solve it ahead of time?
Collatz in C 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 67th Luca2812 833 78 2ms 4 Mar 2024 67th 0xV0RT3X 833 78 2ms 4 Mar 2024 67th dokutan 833 78 2ms 17 Mar 2024 67th BlankSpruce 833 78 3ms 20 Aug 2024 67th madeforlosers 833 78 2ms 5 Sep 2024 67th rniii 833 78 2ms 24 Sep 2024 67th FragmentedCurve 833 78 14ms 3 Oct 2024 67th FortuiteMan 🇫🇷 833 78 2ms 10 Oct 2024 67th Iznoanygod 🇺🇸 833 78 2ms 19 Dec 2024 67th LvLError 833 78 2ms 29 May 2025 67th Lv0Sys 🇵🇱 833 78 2ms 30 May 2025 92nd c0d3-4-F00d 🇩🇪 823 79 2ms 5 May 2022 92nd jgbaldwinbrown 823 79 2ms 16 Jun 2022 92nd jupj 🇫🇮 823 79 2ms 12 Aug 2022 92nd tkr-sh 🇰🇵 823 79 2ms 20 Aug 2022 92nd djeedjay 🇳🇱 823 79 2ms 15 Sep 2022 92nd ValentinCassayre 823 79 2ms 8 Oct 2022 92nd namcartoon06 823 79 2ms 30 Jun 2023 92nd Us1ngTh3Hub 823 79 2ms 8 Jul 2023 92nd Widgitty 823 79 2ms 30 Aug 2023 92nd Grrisly 823 79 2ms 10 Nov 2023 92nd trist224 🇫🇷 823 79 2ms 14 Feb 2024 92nd mathisfun271 823 79 2ms 19 Feb 2024 92nd retrohun 823 79 2ms 29 Mar 2024 92nd HumanoidCPU 823 79 2ms 6 May 2024 92nd funnyboy-roks 823 79 2ms 14 Jun 2024 92nd csharpython 823 79 2ms 5 Aug 2025 92nd iczelia 🇩🇪 823 79 2ms 16 Oct 2025 92nd luuumine 🇫🇷 823 79 2ms 28 Oct 2025 92nd warmCabin 823 79 3ms 3 hours ago 111th Seek64 🇩🇪 813 80 2ms 11 Nov 2022 111th tvcv901 813 80 2ms 22 Mar 2023 111th kyleclaassen 813 80 2ms 20 May 2023 111th logvp 813 80 2ms 1 Feb 2024 111th ei14 813 80 2ms 9 May 2024 111th elttil 813 80 2ms 8 Jun 2024 111th bac0id 813 80 2ms 29 Jun 2024 111th gastropner 813 80 2ms 14 Jul 2025 111th yoikolover 813 80 2ms 19 days ago 120th MinorLegato 🇸🇪 802 81 2ms 9 May 2022 120th slerpyyy 🇩🇪 802 81 2ms 21 Oct 2022 120th violeta-desantis 802 81 2ms 22 Sep 2023 120th SebastianoTaddei 802 81 2ms 4 Oct 2024 124th Ripick 793 82 2ms 10 Nov 2022 124th pandapawskat 793 82 2ms 13 Jan 2023 124th annoj 793 82 2ms 18 Jan 2023 124th CatsAreFluffy 793 82 2ms 18 Feb 2023 124th nyoshe 793 82 2ms 9 Dec 2023 124th NickTheEASDude 🇺🇸 793 82 2ms 26 Jan 2024 124th LHLaurini 🇧🇷 793 82 2ms 26 Jun 2024 124th lgrandco 793 82 2ms 9 Oct 2024 124th Maashau 793 82 2ms 29 Nov 2025 133rd Anonymousellama21 783 83 2ms 15 Jun 2022 133rd cmayer777 783 83 2ms 15 Oct 2022 133rd nstearns96 🇬🇧 783 83 2ms 16 Nov 2022 133rd osmith93 783 83 2ms 13 Dec 2022 133rd mhgockel 783 83 2ms 15 Apr 2023 133rd funnsam 🇭🇰 783 83 2ms 25 Jul 2023 133rd mousetail 🇳🇱 783 83 2ms 10 May 2024 133rd solisolu 783 83 2ms 27 days ago 141st guilhem-roy 🇫🇷 774 84 3ms 5 May 2022 141st resetcentral 774 84 2ms 22 May 2022 141st Adrien-AM 774 84 2ms 12 Sep 2022 141st ibrahimhanifceker 774 84 2ms 9 Aug 2024 141st James-Oswald 🇺🇸 774 84 2ms 23 Aug 2024 141st h-hh-hhh 🇺🇦 774 84 2ms 6 Nov 2024 141st kellantech 774 84 2ms 14 days ago 148th ms-tingliang 765 85 2ms 5 Aug 2022 148th aubergine-sauce 765 85 2ms 26 May 2023 148th kallmi28 🇨🇿 765 85 2ms 13 Nov 2023 148th azka1368 765 85 2ms 23 Nov 2023 148th iilegacyyii 765 85 2ms 22 Jan 2024 148th f-tucker 765 85 2ms 6 Feb 2024 148th Stockoh 🇫🇷 765 85 2ms 29 Sep 2024 155th garrisonhh 756 86 2ms 22 Oct 2022 155th tpasfieldERAU 756 86 2ms 5 Nov 2022 155th isaiah0311 756 86 2ms 16 Feb 2023 155th piano-miles 756 86 2ms 30 Mar 2023 159th razetime 747 87 2ms 22 Aug 2022 160th james-downey 739 88 2ms 9 Jul 2022 First Prev 81–160 of 241 Next Last