A119359 Central coefficients of number triangle A119326.

0, 1, 1, 7, 31, 106, 386, 1499, 5755, 21886, 83854, 323302, 1248534, 4828916, 18719364, 72711123, 282867795, 1101981430, 4298723990, 16788997874, 65641296578, 256895812108, 1006307847324, 3945185527582, 15478851119966

Offset: 0

Author

Paul Barry, May 16 2006

Keywords

• easy
• nonn

Comments

a(n) = A119326(2n,n+1). A119358(n)-a(n) = A071688(n).

Programs

Mathematica

Table[HypergeometricPFQ[{-1/2 - n/2, 1/2 - n/2, 1 - n/2, -n/2}, {1/2, 1/2, 1}, 1] - KroneckerDelta[n], {n, 0, 20}] (* Vladimir Reshetnikov, Oct 04 2016 *)
Table[(2^n Binomial[1/2, (n+1)/2]  + Binomial[n, n/2] Cos[Pi n/2] + n CatalanNumber[n])/2 - KroneckerDelta[n], {n, 0, 20}] (* Vladimir Reshetnikov, Oct 06 2016 *)

Formula

G.f.: (1/sqrt(1-4x)+(1/sqrt(1+4x^2)-1)-c(x)+x*c(-x^2))/2, c(x) the g.f. of A000108;

a(n) = (C(2n,n+1)+C((n-1)/2)*sin(Pi*n/2)-2*0^n-2C(n-1,n/2)*sin(Pi*(n-1)/2))/2.

a(n) = hypergeom([-1/2-n/2, 1/2-n/2, 1-n/2, -n/2], [1/2, 1/2, 1], 1) - 0^n. - Vladimir Reshetnikov, Oct 04 2016