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 A123281 #4 Mar 30 2012 16:50:32 %S A123281 1,1,1,5,19,205,1795,36317,636331,23679901,805351531,56294206205, %T A123281 3735873535339,502757743028605,65725984337422795,17309316971673776957, %U A123281 4485620580863732681131 %N A123281 Leading diagonal of A123260. %D A123281 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1977. %H A123281 R. W. Robinson, <a href="/A123281/b123281.txt">Table of n, a(n) for n = 1..30</a> %K A123281 nonn %O A123281 1,4 %A A123281 _N. J. A. Sloane_, Nov 12 2006