A025275 a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5, with initial values 1,0,1,0.

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,changed

Author

Clark Kimberling

Status

approved