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 A020548 #5 Mar 30 2012 18:36:22 %S A020548 -1,-1,9,649,51841,6825601,1489881601,511943846401,262183528857601, %T A020548 191138113268121601,191138824350351360001,254405870811372994560001, %U A020548 439613359905259699568640001,965830554503712299093852160001 %N A020548 3rd Euler polynomial evaluated at x=n! (multiplied by 4). %K A020548 sign %O A020548 0,3 %A A020548 _Simon Plouffe_