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 A122849 #2 Mar 30 2012 18:59:18
%S A122849 1,0,1,1,1,3,4,6,16,25,46,120,211,441,1156,2233,5104,13581,28351,
%T A122849 69345,188101,419320,1082566,2998776,7074211,19099158,54057004,
%U A122849 133993951,375814531
%N A122849 Diagonal sums of Bessel related triangle A122848.
%F A122849 a(n)=sum{k=0..floor(n/2), k!*C(n-k,k)/((3k-n)!*2^(n-2k))}
%K A122849 easy,nonn
%O A122849 0,6
%A A122849 _Paul Barry_, Sep 14 2006