A113985 Column 2 of triangle A113983; also a(n) = A113983(n+1,1) + [A113983^2](n,1).

1, 3, 7, 17, 45, 135, 463, 1817, 8121, 41075, 233471, 1480945, 10412589, 80634431, 683674831, 6312152353, 63144706753, 681317547507, 7896054343495, 97919789763073, 1294863406981789, 18200820837825479, 271147632138373599

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Formula

a(n) = [A113983^2](n, 0) + [A113983^3](n-1, 0) = A113989(n) + A113994(n-1).

Prog

(PARI) a(n)=local(A, B); A=Mat(1); for(m=2, n+3, 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+3, 3]

Crossrefs

Cf. A113983, A113984 (column 1), A113986 (column 3), A113987 (column 4).

Sequence in context: A233656 A106191 A062810 * A309302 A320774 A151265

Adjacent sequences: A113982 A113983 A113984 * A113986 A113987 A113988

Keyword

nonn

Author

Paul D. Hanna, Nov 12 2005

Status

approved