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 A126153 #3 Mar 30 2012 18:37:02 %S A126153 1,24,636,26304,1650456,147705984,17913816576,2830553662464, %T A126153 565108879101696,139114514096953344,41397845529582959616, %U A126153 14649251145209922945024,6079754611331559564097536 %N A126153 Secondary diagonal of symmetric triangle A126150: a(n) = A126150(n+1,n). %F A126153 a(n) = A126152(n+1) - 3*A126152(n), where A126152 is the main diagonal of triangle A126150. %Y A126153 Cf. A126150; A126151 (column 0), A126152 (diagonal). %K A126153 nonn %O A126153 0,2 %A A126153 _Paul D. Hanna_, Dec 19 2006