A121393 Column 2 of triangle A121391, where column k of T=A121391 equals column k of T^(k+1) shift down 1 row.

1, 1, 3, 12, 58, 333, 2268, 18281, 173127, 1905500, 24080964, 345381551, 5563259860, 99716732043, 1973012968122, 42792555114812, 1011125250589597, 25886430637780776, 714600877541340733, 21178498962170286988

Offset

0,3

Comments

Also equal to column 2 (shifted 1 place) of the matrix cube of triangle A121391.

Links

Table of n, a(n) for n=0..19.

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^j)[i-1, j]); )); A=B); return(A[n+3, 3])}

Crossrefs

Cf. A121391 (triangle), A121392 (column 1), A121394 (column 3).

Sequence in context: A059440 A020075 A020030 * A003316 A298419 A126959

Adjacent sequences: A121390 A121391 A121392 * A121394 A121395 A121396

Keyword

nonn

Author

Paul D. Hanna, Jul 27 2006

Status

approved