This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A120310 #6 Nov 12 2013 15:36:44 %S A120310 98,72,77,49,54,20,10,1,11,2,13,4,17,8,25,7,1,2,2,6,3,12,4,20,5,15,20, %T A120310 13,18,11,0,0,4,9,8,18,12,27 %N A120310 See comments lines. %C A120310 Comment from _Joshua Zucker_, May 26 2007. This appears to be a concatenation of five puzzles: %C A120310 98,72,77,49,54,20,25,10,15,5,10,0,5,5,10,0,5,5,10,0,... (start with 98, then write down the product of its digits, then add 5, repeat) - see A129887. %C A120310 10,1,11,2,13,4,17,8,25,7,... (start with 10; write down the sum of its digits; add last two terms; repeat) - see A129888. %C A120310 1,2,2,6,3,12,4,20,5,30,6,42,... (write down n, then n(n+1)) - see A129889. %C A120310 15,20,13,18,11,16,9,14,... (interleave two arithmetic progressions of difference -2). %C A120310 0,0,4,9,8,18,12,27,16,36,20,... (interleave two arithmetic progressions 0,4,8,12,... and 0,9,18,27,...) %K A120310 nonn,dumb,unkn %O A120310 1,1 %A A120310 Sydney Richardson (AmyNStiers(AT)aol.com), Aug 16 2006