The Calendar hole will go live in approximately 7 days. Why not try and solve it ahead of time?
Collatz in Python 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 635th OCNeve 620 92 19ms 17 Jun 2024 635th themoonisacheese 620 92 22ms 25 Feb 2025 635th BabySharkHi 620 92 20ms 22 Apr 2025 635th arjunarya1 620 92 16ms 28 Aug 2025 635th TJK-S 620 92 18ms 10 Oct 2025 646th Bananapants22 613 93 28ms 4 Sep 2022 646th jaxmattfair 🇺🇸 613 93 19ms 10 Jan 2023 646th fenix-bear 613 93 19ms 18 Nov 2023 646th epic-programmer-guy 613 93 23ms 22 Dec 2023 646th brimstonetrader 613 93 22ms 18 Nov 2024 651st atazzam 🇺🇸 606 94 17ms 18 May 2022 651st rohangpta 606 94 16ms 8 Aug 2022 651st shinylego 606 94 18ms 14 Sep 2022 651st sgaltair 606 94 20ms 4 Nov 2022 651st TotoAJ 606 94 19ms 15 Dec 2023 651st Gusic06 606 94 18ms 6 May 2024 651st kyleyarwood 606 94 20ms 6 Oct 2024 651st jj0786-cell 606 94 19ms 1 Apr 2025 651st griffinschreiber 606 94 19ms 1 Apr 2025 651st o800 606 94 17ms 17 Nov 2025 661st felixcroc 600 95 18ms 30 Mar 2023 661st Pyro569 600 95 19ms 4 Jul 2023 661st rm-rf-innocence 600 95 19ms 19 Dec 2023 661st Bit125 600 95 19ms 30 Jan 2024 661st aalec 600 95 20ms 25 Apr 2024 661st strogor 600 95 19ms 13 Jun 2025 661st cthierfelder 🇲🇨 600 95 19ms 17 Jul 2025 661st ThomasDelepine 600 95 24ms 29 Oct 2025 669th karhuthebear 594 96 24ms 9 May 2022 669th qwjhvbxi 594 96 19ms 6 Feb 2024 669th alfonsoalves 594 96 18ms 21 Jul 2024 669th jeff-re 594 96 15ms 1 Apr 2025 673rd a-penton 588 97 15ms 22 Sep 2022 673rd jrbud 588 97 18ms 6 Jan 2024 673rd befoster 588 97 23ms 22 Feb 2024 673rd joshua-el-samalouti 🇩🇪 588 97 22ms 26 May 2024 673rd luca1339 588 97 18ms 10 Jun 2024 678th lukemalek 582 98 15ms 10 Oct 2022 678th UltimateGuy0987 582 98 20ms 14 Oct 2022 678th TheLazySquid 582 98 21ms 20 Dec 2022 678th StronkCheese 🇺🇸 582 98 19ms 13 Mar 2023 678th Anthony-Williams-06 582 98 29ms 17 Oct 2023 678th abcdhhhh 582 98 17ms 27 Aug 2024 678th OSYCh314 🇦🇺 582 98 24ms 16 Nov 2024 678th cole-wilson 582 98 19ms 9 Dec 2024 678th Akilles1 582 98 21ms 15 May 2025 678th Hyperoplex145 582 98 18ms 11 Nov 2025 688th LukeRichardson-dev 576 99 15ms 12 May 2022 688th Tagfox 576 99 18ms 18 Jul 2022 688th gabrielsqw 576 99 23ms 24 Oct 2023 688th sciencedjinn 576 99 16ms 8 Nov 2024 688th MrNiknoc 576 99 18ms 15 Jun 2025 693rd OppositeShark 570 100 18ms 19 Jul 2022 693rd NOS4A5I 570 100 17ms 10 Jan 2023 693rd lomarbrick 570 100 17ms 16 May 2023 693rd karlaacastro44 570 100 19ms 5 May 2025 697th markus-rekdal 564 101 24ms 10 May 2022 697th fraserli 🇦🇺 564 101 25ms 2 May 2023 697th FCORMERAIS 564 101 17ms 6 Mar 2024 697th yhm138 564 101 13ms 16 Feb 2025 697th MinecraftFan69420 564 101 21ms 31 Oct 2025 702nd AndersH3 🇸🇪 559 102 14ms 17 May 2023 702nd JulieGermainUNT 559 102 20ms 2 Apr 2025 702nd NicoBliss 559 102 22ms 16 Nov 2025 705th rajlath 553 103 21ms 7 Jan 2023 705th mnurzia 553 103 15ms 12 Oct 2023 705th sqrteipi 553 103 19ms 2 Apr 2024 705th calum12345 553 103 19ms 26 Mar 2025 705th SectorCorruptor 553 103 24ms 14 Aug 2025 710th winigo3 548 104 23ms 8 Aug 2022 710th zt14427 548 104 19ms 30 Apr 2023 710th IoLimmer 548 104 19ms 24 Jul 2024 713th LordSir101 543 105 17ms 19 Jul 2022 713th tmanternach 543 105 19ms 24 Nov 2022 713th weber-hge 543 105 15ms 13 Jun 2023 713th Eugen-str 543 105 19ms 24 Oct 2023 717th ms-tingliang 538 106 14ms 5 Aug 2022 717th achilleasr 538 106 18ms 7 Nov 2022 717th OleBrumm 538 106 19ms 8 Jan 2023 717th AbhilashaTandon 538 106 23ms 19 Sep 2023 First Prev 641–720 of 813 Next Last