A113987 Column 4 of triangle A113983; also a(n) = A113983(n+3,3) + [A113983^2](n+2,3).

1, 5, 21, 89, 401, 1969, 10633, 63297, 414857, 2984829, 23485909, 201272257, 1870901681, 18786935025, 203013976769, 2352251860561, 29124175447169, 384114020063301, 5380529664829157, 79829102054901081, 1251315569536252353

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = [A113983^4](n, 0) + [A113983^5](n-1, 0) = A113995(n) + A113996(n-1).

Prog

(PARI) a(n)=local(A, B); A=Mat(1); for(m=2, n+5, B=matrix(m, m); for(i=1, m, for(j=1, i, if(i<3 || j==1 || j==i, B[i, j]=1, B[i, j]=A[i-1, j-1]+(A^2)[i-2, j-1]); )); A=B); A[n+5, 5]

Crossrefs

Cf. A113983, A113984 (column 1), A113985 (column 2), A113986 (column 3).

Sequence in context: A015448 A273796 A035011 * A188707 A360580 A333538

Adjacent sequences: A113984 A113985 A113986 * A113988 A113989 A113990

Keyword

nonn

Author

Paul D. Hanna, Nov 12 2005

Status

approved