A121397 - OEIS

A121397

Column 2 of triangle T=A121395, where column k of T equals column k of T^(2^k) shift down 1 row.

%I #3 Mar 30 2012 18:36:58

%S 1,1,4,22,164,1837,34176,1106012,63053480,6385424679,1160549661044,

%T 382452061644152,230599430810507856,256385360437413619926,

%U 529174935800200166078372,2039277788771681728279205788

%N Column 2 of triangle T=A121395, where column k of T equals column k of T^(2^k) shift down 1 row.

%C Also equals column 2 (shifted 1 place) of the matrix 4th power of triangle A121395.

%o (PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+3, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i,B[i, j]=1, B[i, j]=(A^(2^(j-1)))[i-1, j]); )); A=B); return(A[n+3, 3])}

%Y Cf. A121395 (triangle), A121396 (column 1).

%K nonn

%O 0,3

%A _Paul D. Hanna_, Jul 27 2006