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 A111780 #3 Oct 12 2012 14:40:23 %S A111780 1,42,1204,29736,689850,15647940,354718980,8137289160,190349674515, %T A111780 4561677870750,112317990384600,2846259737521200,74306186469414900, %U A111780 1999421553976446600,55458660913310655000,1585528821898619598000 %N A111780 Seventh column (m=6) of unsigned triangle A111595. %F A111780 E.g.f. (1/sqrt(1-x^2))*((x/(1-x))^6)/6!. %F A111780 a(n)=(n!/6!)*sum(binomial(2*k, k)*binomial(n-2*k-1, 5)/(4^k), k=0..floor((n-6)/2)), n>=6. %K A111780 nonn,easy %O A111780 6,2 %A A111780 _Wolfdieter Lang_, Aug 23 2005