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 A104445 #6 Jun 13 2017 01:29:49 %S A104445 1,1,1,1,1,1,1,2,1,1,1,4,3,1,1,1,9,9,4,1,1,1,24,30,16,5,1,1,1,77,115, %T A104445 70,25,6,1,1,1,295,510,344,135,36,7,1,1,1,1329,2602,1908,805,231,49,8, %U A104445 1,1,1,6934,15133,11904,5325,1616,364,64,9,1,1,1,41351,99367,83028,39001 %N A104445 Triangular matrix T, read by rows, that satisfies: SHIFT_LEFT_UP(T) = T^2 - T + I, or, equivalently: T(n+1,k+1) = [T^2](n,k) - T(n,k) + [T^0](n,k) for n>=k>=0, with T(0,0)=1. %C A104445 Surprisingly, SHIFT_UP(T) = A091351, or T(n+1,k) = A091351(n,k) for n>=k>=0, where column k of A091351 equals column 0 of A091351^(k+1) for k>=0. %F A104445 T(n, k) = Sum_{j=0..n-k-1} T(n-k, j)*T(j+k, k-1) for n>k>0 with T(n, 0)=T(n, n)=1 (n>=0). %e A104445 Rows begin: %e A104445 1; %e A104445 1,1; %e A104445 1,1,1; %e A104445 1,2,1,1; %e A104445 1,4,3,1,1; %e A104445 1,9,9,4,1,1; %e A104445 1,24,30,16,5,1,1; %e A104445 1,77,115,70,25,6,1,1; %e A104445 1,295,510,344,135,36,7,1,1; %e A104445 1,1329,2602,1908,805,231,49,8,1,1; %e A104445 1,6934,15133,11904,5325,1616,364,64,9,1,1; ... %o A104445 (PARI) T(n,k)=if(n<k || k<0,0,if(n==k || k==0,1, sum(j=0,n-k-1,T(n-k,j)*T(j+k,k-1)))) %Y A104445 Cf. A091351, A104446 (matrix square); columns form: A091352, A091353, A091354. %K A104445 nonn,tabl %O A104445 0,8 %A A104445 _Paul D. Hanna_, Mar 07 2005