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 A171589 #14 Sep 08 2013 19:59:26
%S A171589 1,4,1,17,8,1,77,50,12,1,371,290,99,16,1,1890,1647,703,164,20,1,10095,
%T A171589 9366,4644,1380,245,24,1,56040,53853,29592,10434,2385,342,28,1,320795,
%U A171589 314234,185411,74084,20345,3782,455,32,1
%N A171589 Riordan array (f(x), x*f(x)) where f(x) is the g.f. of A104455.
%C A171589 Equal to B*A171568 = A125906*B^(-1), B = A007318.
%F A171589 T(n,0)-T(n,1)=3^n.
%F A171589 T(n,k) = T(n-1,k-1) + 4*T(n-1,k) + sum_{i, i>=0} T(n-1,k+1+i). - _Philippe Deléham_, Feb 23 2012
%e A171589 Triangle begins :
%e A171589 1
%e A171589 4, 1
%e A171589 17, 8, 1
%e A171589 77, 50, 12, 1
%e A171589 371, 290, 99, 16, 1
%e A171589 1890, 1647, 703, 164, 20, 1
%e A171589 10095, 9366, 4644, 1380, 245, 24, 1
%e A171589 Production matrix begins
%e A171589 4, 1
%e A171589 1, 4, 1
%e A171589 1, 1, 4, 1
%e A171589 1, 1, 1, 4, 1
%e A171589 1, 1, 1, 1, 4, 1
%e A171589 1, 1, 1, 1, 1, 4, 1
%e A171589 1, 1, 1, 1, 1, 1, 4, 1
%e A171589 1, 1, 1, 1, 1, 1, 1, 4, 1
%e A171589 ... - _Philippe Deléham_, Mar 05 2013
%Y A171589 Cf. A104455, A125906, A171568,
%K A171589 nonn,tabl
%O A171589 0,2
%A A171589 _Philippe Deléham_, Dec 12 2009