A025275 a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5.

1, 0, 1, 0, 0, 1, 2, 4, 10, 24, 56, 133, 318, 760, 1822, 4384, 10576, 25578, 62020, 150744, 367220, 896496, 2193104, 5375405, 13199606, 32468912, 80000438, 197423104, 487921440, 1207578750, 2992704924, 7426194328, 18449964876, 45890849360

Offset

1,7

Links

Table of n, a(n) for n=1..34.

Formula

Conjecture: n*a(n) +2*(-2*n+3)*a(n-1) +4*(n-3)*a(n-2) +2*(-2*n+9)*a(n-3) +8*(n-6)*a(n-4)=0. - R. J. Mathar, May 30 2014

G.f.: 1/2 - sqrt(8*x^4-4*x^3+4*x^2-4*x+1)/2. - Vaclav Kotesovec, Jan 25 2015

Mathematica

nmax = 30; aa = ConstantArray[0, nmax]; aa[[1]] = 1; aa[[2]] = 0; aa[[3]] = 1; aa[[4]] = 0; Do[aa[[n]] = Sum[aa[[k]]*aa[[n-k]], {k, 1, n-1}], {n, 5, nmax}]; aa (* Vaclav Kotesovec, Jan 25 2015 *)

Crossrefs

Sequence in context: A190794 A052912 A024740 * A165409 A052542 A163271

Adjacent sequences: A025272 A025273 A025274 * A025276 A025277 A025278

Keyword

nonn

Author

Clark Kimberling

Status

approved