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 A111781 #3 Oct 12 2012 14:40:23 %S A111781 1,56,2052,63000,1777050,48149640,1284709140,34260506280,921799753875, %T A111781 25175488338000,700755564108600,19932553764723600,580406741946731700, %U A111781 17320767850295910000,530112107596146075000,16645556950225160958000 %N A111781 Eighth column (m=7) of unsigned triangle A111595. %F A111781 E.g.f. (1/sqrt(1-x^2))*((x/(1-x))^7)/7!. %F A111781 a(n)=(n!/7!)*sum(binomial(2*k, k)*binomial(n-2*k-1, 6)/(4^k), k=0..floor((n-7)/2)), n>=7. %K A111781 nonn,easy %O A111781 7,2 %A A111781 _Wolfdieter Lang_, Aug 23 2005