A121421 Column 0 of triangle A121420.

1, 3, 12, 76, 711, 9054, 147471, 2938176, 69328365, 1891371807, 58575539361, 2030011517685, 77827890696820, 3270046577551695, 149407542447596319, 7374639622066056408, 391044078030333899385, 22168014954558449549349

Offset

0,2

Comments

Also column 2 of square array A136733.

A121420 is the matrix cube of triangle A121412; row n of triangle T=A121412 equals row (n-1) of T^(n+1) with an appended '1'.

Links

Table of n, a(n) for n=0..17.

Prog

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

Crossrefs

Cf. A121420 (triangle); other columns: A121422, A121423.

Cf. A136733; A101483, A121418; A121425.

Sequence in context: A032114 A193162 A060946 * A349884 A108043 A058561

Adjacent sequences: A121418 A121419 A121420 * A121422 A121423 A121424

Keyword

nonn

Author

Paul D. Hanna, Aug 23 2006

Extensions

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

Status

approved