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 A115190 #4 Sep 26 2012 04:24:38 %S A115190 1,121,1762,20989,235543,2588641,28259704,308277688,3369314986, %T A115190 36937817182,406378312834,4487124168115,49722977591155, %U A115190 552884158181785,6167643983348920,69012419067802540,774413615153430670 %N A115190 Fourth diagonal (M=4) of triangle A115154 (called Y(3,1)). %F A115190 a(n)= A115154(n+3,n+1), n>=0. %F A115190 Recurrence: a(n)= b(n) - 9*(b(n-1)-b(n-2)), with b(n):=A064063(n+4), n>=0. %F A115190 G.f.: ((-3+18*x+2*x^3) + 3*(1-9*x+9*x^2)*c(3*x))/((2+x)*x^3), with the o.g.f. c(x) of A000108 (Catalan). %e A115190 a(0)= 1 = 190 - 9*(25-4); a(2) = 1762 = 14506 - 9*(1606-190). %K A115190 nonn,easy %O A115190 0,2 %A A115190 _Wolfdieter Lang_, Feb 23 2006