The Calendar hole will go live in approximately 7 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 800th Betuaredead 867 92 468ms 5 Jan 2023 800th Yax42 🇫🇷 867 92 420ms 4 Oct 2025 803rd emgordon154 867 160 1,744ms 68 mins ago 804th bac0id 866 90 336ms 26 Sep 2023 804th deadp4nda 🇩🇪 866 90 372ms 26 Apr 2024 804th 123mjb 866 90 339ms 23 Jun 2025 804th michelebastione 🇮🇹 866 90 384ms 24 Aug 2025 804th razvandmtr 🇷🇴 866 90 368ms 6 Nov 2025 804th amazingalek 866 90 421ms 4 days ago 810th TylerBloom 866 96 115ms 22 Mar 2024 811th shellbertt 🇨🇦 866 98 63ms 9 May 2022 811th iakolzin 866 98 61ms 26 May 2022 811th Betuaredead 866 98 61ms 5 Jan 2023 811th oceko 866 98 63ms 19 Feb 2024 811th dokutan 866 98 61ms 17 Mar 2024 811th cuzdav 866 98 60ms 4 May 2025 811th timhaj 🇸🇮 866 98 61ms 12 Sep 2025 811th Yax42 🇫🇷 866 98 60ms 4 Oct 2025 819th 5quiwyrm 865 52 249ms 4 Sep 2022 819th MeWhenI 🇻🇦 865 52 280ms 28 Jan 2023 819th Feniske 🇫🇷 865 52 280ms 7 Nov 2023 819th dcgjb 865 52 297ms 29 Jan 2024 819th JPRuskin 🇬🇧 865 52 278ms 7 Apr 2025 819th IISResetMe 865 52 267ms 7 Apr 2025 819th Ripick 865 52 251ms 1 Jun 2025 826th Andriamanitra 🇫🇮 865 67 144ms 26 Apr 2023 827th MeWhenI 🇻🇦 865 81 8ms 23 May 2023 828th typeswitch-dev 🇵🇹 864 75 5ms 22 Jul 2023 829th DialFrost 🇸🇬 864 86 18ms 15 Dec 2024 830th Setvizan 863 62 10ms 12 Jan 2023 830th GreenBeansAgainstVeganism 863 62 10ms 13 Jan 2023 830th arctouch-cristiannevianna 863 62 10ms 3 Apr 2023 830th Corxldyphik 863 62 10ms 11 Apr 2023 830th Blockyheadman 863 62 10ms 1 Nov 2023 830th ollyspooner 863 62 10ms 22 Nov 2023 830th itserasmus 863 62 10ms 25 Jan 2024 830th Jacob385 863 62 10ms 13 Mar 2024 830th junkondo-jp 863 62 11ms 30 Jun 2024 830th ShiraJoseph 🇺🇸 863 62 9ms 1 Mar 2025 830th tomh1012 863 62 9ms 21 days ago 841st MeWhenI 🇻🇦 863 145 526ms 28 Mar 2025 842nd HPWiz 🇳🇿 862 50 249ms 4 May 2022 842nd JayXon 🇺🇸 862 50 254ms 5 May 2022 842nd Steffan153 🇫🇮 862 50 287ms 10 Dec 2022 842nd ovs-code 🇩🇪 862 50 389ms 24 Oct 2023 842nd sean-niemann 🇺🇸 862 50 271ms 12 Jul 2024 847th 386asm 🇺🇸 862 86 40ms 9 Apr 2023 848th ovs-code 🇩🇪 862 161 1,719ms 14 Sep 2025 848th Yewzir 🇧🇪 862 161 2,399ms 14 Nov 2025 850th Shanethegamer 🇺🇸 861 58 767ms 17 Sep 2025 851st Shanethegamer 🇺🇸 861 70 99ms 12 Dec 2022 851st Alessandro-Balconi 🇮🇹 861 70 95ms 26 Dec 2022 853rd NewDefectus 🇮🇱 861 73 3ms 6 May 2022 853rd Natanaelel 🇸🇪 861 73 3ms 15 Jun 2022 853rd LorenzoDeGaspari 861 73 2ms 27 May 2024 853rd Bpc-CPU 861 73 2ms 12 Jul 2025 853rd AZTECCO 861 73 2ms 16 Sep 2025 853rd CaedenHarper 🇨🇦 861 73 2ms 28 Sep 2025 853rd prestosilver 🇺🇸 861 73 2ms 21 days ago 860th Liibe 860 97 391ms 25 Sep 2025 861st stefangimmillaro 860 112 268ms 26 Sep 2023 861st kkoenig 860 112 287ms 4 Jan 2024 863rd o0lit3 🇺🇸 859 54 7ms 22 Jun 2023 863rd Natanaelel 🇸🇪 859 54 7ms 10 Feb 2025 865th scpchicken 🇵🇼 859 72 19ms 4 May 2022 865th sultan 859 72 17ms 6 Jun 2022 865th annaproxy 859 72 20ms 22 Aug 2022 865th BlankSpruce 859 72 23ms 9 Sep 2022 865th ValentinCassayre 859 72 21ms 8 Oct 2022 865th mathb0y512 859 72 21ms 1 Dec 2022 865th NoahBolohan 🇨🇦 859 72 21ms 28 Feb 2023 865th neel11235813 859 72 21ms 8 Mar 2023 865th Kacarott 🇦🇺 859 72 16ms 24 Mar 2023 865th Fracture17 859 72 20ms 8 Apr 2023 865th ayushdewan 859 72 23ms 7 May 2023 865th PeterTillema 🇳🇱 859 72 24ms 17 Oct 2023 865th Glinte 859 72 24ms 11 Dec 2023 865th nanatsu8 859 72 24ms 11 May 2024 865th thej10n 859 72 18ms 12 Jun 2024 865th tobeannouncd 859 72 16ms 25 Apr 2025 First Prev 801–880 of 3,503 Next Last