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 800th deadp4nda 🇩🇪 866 90 372ms 26 Apr 2024 800th 123mjb 866 90 352ms 23 Jun 2025 800th michelebastione 🇮🇹 866 90 384ms 24 Aug 2025 800th razvandmtr 🇷🇴 866 90 385ms 6 Nov 2025 800th amazingalek 866 90 429ms 2 days ago 806th TylerBloom 866 96 115ms 22 Mar 2024 807th shellbertt 🇨🇦 866 98 66ms 9 May 2022 807th iakolzin 866 98 85ms 26 May 2022 807th Betuaredead 866 98 78ms 5 Jan 2023 807th oceko 866 98 73ms 19 Feb 2024 807th dokutan 866 98 81ms 17 Mar 2024 807th cuzdav 866 98 62ms 4 May 2025 807th timhaj 🇸🇮 866 98 82ms 12 Sep 2025 807th Yax42 🇫🇷 866 98 75ms 4 Oct 2025 815th 5quiwyrm 865 52 300ms 4 Sep 2022 815th MeWhenI 🇻🇦 865 52 280ms 28 Jan 2023 815th Feniske 🇫🇷 865 52 280ms 7 Nov 2023 815th dcgjb 865 52 297ms 29 Jan 2024 815th JPRuskin 🇬🇧 865 52 313ms 7 Apr 2025 815th IISResetMe 865 52 267ms 7 Apr 2025 815th Ripick 865 52 266ms 1 Jun 2025 822nd Andriamanitra 🇫🇮 865 67 144ms 26 Apr 2023 823rd MeWhenI 🇻🇦 865 81 8ms 23 May 2023 824th typeswitch-dev 🇵🇹 864 75 5ms 22 Jul 2023 825th DialFrost 🇸🇬 864 86 18ms 15 Dec 2024 826th Setvizan 863 62 10ms 12 Jan 2023 826th GreenBeansAgainstVeganism 863 62 10ms 13 Jan 2023 826th arctouch-cristiannevianna 863 62 10ms 3 Apr 2023 826th Corxldyphik 863 62 10ms 11 Apr 2023 826th Blockyheadman 863 62 10ms 1 Nov 2023 826th ollyspooner 863 62 10ms 22 Nov 2023 826th itserasmus 863 62 10ms 25 Jan 2024 826th Jacob385 863 62 10ms 13 Mar 2024 826th junkondo-jp 863 62 11ms 30 Jun 2024 826th ShiraJoseph 🇺🇸 863 62 9ms 1 Mar 2025 826th tomh1012 863 62 9ms 19 days ago 837th MeWhenI 🇻🇦 863 145 526ms 28 Mar 2025 838th HPWiz 🇳🇿 862 50 346ms 4 May 2022 838th JayXon 🇺🇸 862 50 313ms 5 May 2022 838th Steffan153 🇫🇮 862 50 287ms 10 Dec 2022 838th ovs-code 🇩🇪 862 50 418ms 24 Oct 2023 838th sean-niemann 🇺🇸 862 50 344ms 12 Jul 2024 843rd 386asm 🇺🇸 862 86 40ms 9 Apr 2023 844th ovs-code 🇩🇪 862 161 1,719ms 14 Sep 2025 844th Yewzir 🇧🇪 862 161 2,399ms 14 Nov 2025 846th Shanethegamer 🇺🇸 861 58 767ms 17 Sep 2025 847th Shanethegamer 🇺🇸 861 70 99ms 12 Dec 2022 847th Alessandro-Balconi 🇮🇹 861 70 95ms 26 Dec 2022 849th NewDefectus 🇮🇱 861 73 3ms 6 May 2022 849th Natanaelel 🇸🇪 861 73 3ms 15 Jun 2022 849th LorenzoDeGaspari 861 73 2ms 27 May 2024 849th Bpc-CPU 861 73 2ms 12 Jul 2025 849th AZTECCO 861 73 2ms 16 Sep 2025 849th CaedenHarper 🇨🇦 861 73 2ms 28 Sep 2025 849th prestosilver 🇺🇸 861 73 2ms 19 days ago 856th Liibe 860 97 391ms 25 Sep 2025 857th stefangimmillaro 860 112 268ms 26 Sep 2023 857th kkoenig 860 112 287ms 4 Jan 2024 859th o0lit3 🇺🇸 859 54 7ms 22 Jun 2023 859th Natanaelel 🇸🇪 859 54 7ms 10 Feb 2025 861st scpchicken 🇵🇼 859 72 19ms 4 May 2022 861st sultan 859 72 17ms 6 Jun 2022 861st annaproxy 859 72 20ms 22 Aug 2022 861st BlankSpruce 859 72 23ms 9 Sep 2022 861st ValentinCassayre 859 72 21ms 8 Oct 2022 861st mathb0y512 859 72 21ms 1 Dec 2022 861st NoahBolohan 🇨🇦 859 72 21ms 28 Feb 2023 861st neel11235813 859 72 21ms 8 Mar 2023 861st Kacarott 🇦🇺 859 72 16ms 24 Mar 2023 861st Fracture17 859 72 20ms 8 Apr 2023 861st ayushdewan 859 72 23ms 7 May 2023 861st PeterTillema 🇳🇱 859 72 24ms 17 Oct 2023 861st Glinte 859 72 24ms 11 Dec 2023 861st nanatsu8 859 72 24ms 11 May 2024 861st thej10n 859 72 18ms 12 Jun 2024 861st tobeannouncd 859 72 16ms 25 Apr 2025 861st YAJUE114514 859 72 16ms 15 Aug 2025 861st snoozingnewt 🇨🇦 859 72 23ms 16 days ago 879th aditsu 859 77 3,684ms 23 Nov 2025 880th Yewzir 🇧🇪 858 65 4ms 9 Oct 2023 First Prev 801–880 of 3,497 Next Last