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 A031176 #12 Feb 16 2025 08:32:35 %S A031176 1,1,8,8,8,8,8,1,8,8,1,8,8,1,8,8,8,8,8,1,8,8,8,1,8,8,8,8,1,8,8,1,1,8, %T A031176 8,8,8,8,8,8,8,8,8,8,1,8,8,8,8,1,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, %U A031176 1,8,1,8,8,8,8,8,8,8,8,1,8,8,1,8,8,8,1,8,8,8,8,1,8,8,1,8,8,1,8,8 %N A031176 Periods of sum of squares of digits iterated until the sequence becomes periodic. %H A031176 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Digitaddition.html">Digit addition.</a> %Y A031176 Cf. A003132, A099645. [From _R. J. Mathar_, May 31 2009] %K A031176 nonn,base %O A031176 0,3 %A A031176 _Eric W. Weisstein_ %E A031176 The value a(0)=1 was added by _R. J. Mathar_, May 31 2009