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 A098496 #7 Jul 28 2015 21:47:03
%S A098496 1,1,-1,-3,0,5,-2,-6,18,-28,-9,232,-949,2147,579,-34487,202078,
%T A098496 -680541,527630,11789818,-104485820,520965294,-1270746269,-5790611092,
%U A098496 98629011681,-729706466727,3269817273787,-2007499839343,-131143854669640,1558206734632453
%N A098496 Antidiagonal sums of triangle A098495.
%t A098496 T[r_, 1] := 1; T[r_, 2] := -r - 1; T[r_, c_] := -r*T[r, c - 1] - T[r, c - 2]; Table[ Sum[ T[n - i, i], {i, n + 1}], {n, 0, 12}] (* _Robert G. Wilson v_, May 10 2005 *)
%K A098496 sign
%O A098496 0,4
%A A098496 _Ralf Stephan_, Sep 12 2004
%E A098496 More terms from _Robert G. Wilson v_, May 10 2005