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 A012801 #4 Feb 24 2012 12:51:09 %S A012801 1,1,1,2,5,40,205,576,2473,46208,475385,1293184,-2814227,309637120, %T A012801 5900398725,5786437632,-532397600303,7315622592512,273302104270705, %U A012801 -347058934743040,-68724093821987755,483735262691819520 %N A012801 exp(sec(x)*arctan(x))=1+x+1/2!*x^2+2/3!*x^3+5/4!*x^4+40/5!*x^5... %K A012801 sign %O A012801 0,4 %A A012801 Patrick Demichel (patrick.demichel(AT)hp.com)