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 A031212 #13 Feb 16 2025 08:32:36 %S A031212 1,1,30,93,1,19,80,4,30,80,1,30,93,4,10,80,24,30,80,28,30,93,8,30,80, %T A031212 28,19,93,8,30,93,4,30,80,8,30,93,8,10,93,1,10,80,8,10,93,28,30,80,28, %U A031212 19,80,28,30,93,8,30,93,8,30,80,24,19,93,28,30,80,4,30,80,4,30 %N A031212 Periods of sum of 9th powers of digits iterated until the sequence becomes periodic. %H A031212 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Digitaddition.html">Digitaddition</a> %K A031212 nonn,base %O A031212 0,3 %A A031212 _Eric W. Weisstein_ %E A031212 Missing a(0)=1 inserted by _Sean A. Irvine_, Apr 15 2020