A135882 Column 1 of triangle A135880.

1, 2, 7, 34, 215, 1698, 16220, 182714, 2378780, 35219202, 585245185, 10797322816, 219163958124, 4856832298391, 116735215192864, 3025759884533190, 84155831914971391, 2500599947944218716, 79072271422935678302

Offset

0,2

Links

Paul D. Hanna, Table of n, a(n) for n = 0..79

Example

Equals column 1 of triangle P=A135880:
1;
1, 1;
2, 2, 1;
6, 7, 3, 1;
25, 34, 15, 4, 1;
138, 215, 99, 26, 5, 1;
970, 1698, 814, 216, 40, 6, 1; ...
where column k of P^2 equals column 0 of P^(2k+2)
such that column 0 of P^2 equals column 0 of P shift left.

Prog

(PARI) {a(n)=local(P=Mat(1), R, PShR); if(n==0, 1, for(i=0, n, PShR=matrix(#P, #P, r, c, if(r>=c, if(r==c, 1, if(c==1, 0, P[r-1, c-1])))); R=P*PShR; R=matrix(#P+1, #P+1, r, c, if(r>=c, if(r<#P+1, R[r, c], if(c==1, (P^2)[ #P, 1], (P^(2*c-1))[r-c+1, 1])))); P=matrix(#R, #R, r, c, if(r>=c, if(r<#R, P[r, c], (R^c)[r-c+1, 1])))); P[n+2, 2])}

Crossrefs

Cf. A135880; other columns: A135881, A135883, A135884.

Sequence in context: A177401 A171792 A185324 * A143740 A049463 A294466

Adjacent sequences: A135879 A135880 A135881 * A135883 A135884 A135885

Keyword

nonn

Author

Paul D. Hanna, Dec 15 2007

Extensions

Error in entries (false comma) corrected by N. J. A. Sloane, Jan 23 2008

Status

approved