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

Author

Paul D. Hanna, Aug 26 2006

Keywords

• nonn

Comments

Also main diagonal of square array A136737.

Crossrefs

Cf. A121426, A121412.

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

Programs

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])}

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).

Extensions

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