A121427 Main diagonal of rectangular table A121426.

1, 2, 15, 178, 2820, 55410, 1294776, 35003430, 1073540871, 36805249870, 1394346324624, 57831360118800, 2605921998840420, 126757491839620950, 6619466939158637640, 369368127676399990338, 21932876159270004129285

Offset

0,2

Comments

Also main diagonal of square array A136737.

Links

Table of n, a(n) for n=0..16.

Formula

a(n) = [A121412^(n+1)](n+1,1) for n>=0; i.e., (n+1)-th term of column 1 in matrix power A121412^(n+1).

Prog

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

Crossrefs

Cf. A121426, A121412.

Cf. A136737; A121413, A121417, A121422; A136741.

Sequence in context: A036080 A215368 A200795 * A364340 A099709 A208409

Adjacent sequences: A121424 A121425 A121426 * A121428 A121429 A121430

Keyword

nonn

Author

Paul D. Hanna, Aug 26 2006

Extensions

Edited by N. J. A. Sloane, Oct 30 2008 at the suggestion of R. J. Mathar

Status

approved