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 A107674 #12 Mar 11 2021 03:04:58 %S A107674 1,24,4,2268,135,9,461056,15936,448,16,160977375,3789250,69000,1125, %T A107674 25,85624508376,1485395280,19994688,223560,2376,36,64363893844726, %U A107674 862907827866,9138674195,79086196,596820,4459,49,64928246784463872 %N A107674 Matrix square of triangle A107671. %C A107674 Column 0 is A107675. %F A107674 Matrix diagonalization method: define the triangular matrix P by P(n, k) = ((n+1)^3)^(n-k)/(n-k)! for n >= k >= 0 and the diagonal matrix D by D(n, n) = n+1 for n >= 0; then T is given by T = P^-1*D^2*P. %e A107674 Triangle T(n,k) (with rows n >= 0 and columns k = 0..n) begins: %e A107674 1; %e A107674 24, 4; %e A107674 2268, 135, 9; %e A107674 461056, 15936, 448, 16; %e A107674 160977375, 3789250, 69000, 1125, 25; %e A107674 85624508376, 1485395280, 19994688, 223560, 2376, 36; %e A107674 ... %o A107674 (PARI) {T(n,k)=local(P=matrix(n+1,n+1,r,c,if(r>=c,(r^3)^(r-c)/(r-c)!)), D=matrix(n+1,n+1,r,c,if(r==c,r)));if(n>=k,(P^-1*D^2*P)[n+1,k+1])} %Y A107674 Cf. A006690, A107667, A107671, A107675, A107676. %K A107674 nonn,tabl %O A107674 0,2 %A A107674 _Paul D. Hanna_, Jun 07 2005