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 A263621 #5 Oct 23 2015 14:18:20 %S A263621 3,6,13,19,30,36 %N A263621 Appears to be an erroneous version of A263620. %H A263621 G. J. Simmons, <a href="/A002778/a002778_2.pdf">Palindromic powers</a>, J. Rec. Math., 3 (No. 2, 1970), 93-98. [Annotated scanned copy] See page 95. %K A263621 dead %O A263621 1,1 %A A263621 _N. J. A. Sloane_, Oct 23 2015