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 A127498 #3 Mar 30 2012 18:37:03 %S A127498 1,2,5,16,53,186,672,2465,9158,34354,129833,493534,1884955,7227522, %T A127498 27804584,107268790,414852381,1607836478,6243201267,24282747900, %U A127498 94587991975,368940451638,1440796181876,5632827891526,22043782012620 %N A127498 Secondary diagonal of triangle A127496: a(n) = A127496(n+1,n) for n>=0. %Y A127498 Cf. A127496, A127497. %K A127498 nonn %O A127498 0,2 %A A127498 _Paul D. Hanna_, Jan 16 2007