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.

1, 1, 4, 22, 164, 1837, 34176, 1106012, 63053480, 6385424679, 1160549661044, 382452061644152, 230599430810507856, 256385360437413619926, 529174935800200166078372, 2039277788771681728279205788

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OFFSET

0,3

COMMENTS

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

LINKS

Table of n, a(n) for n=0..15.

PROG

(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])}

CROSSREFS

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

Sequence in context: A111343 A302908 A187123 * A067369 A247249 A368319

Adjacent sequences: A121394 A121395 A121396 * A121398 A121399 A121400

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 27 2006

STATUS

approved