A157706 The z^2 coefficients of the polynomials in the GF1 denominators of A156921.

7, 75, 385, 1365, 3850, 9282, 19950, 39270, 72105, 125125, 207207, 329875, 507780, 759220, 1106700, 1577532, 2204475, 3026415, 4089085, 5445825, 7158382, 9297750, 11945050, 15192450, 19144125, 23917257

Offset: 2

Author

Johannes W. Meijer, Mar 07 2009

Keywords

• easy
• nonn

Comments

See A157702 for background information.

Crossrefs

Cf. A156921, A157702.

Programs

Maple

nmax:=27; for n from 0 to nmax do fz(n):= product( (1-(2*m-1)*z)^(n+1-m) , m=1..n); c(n):= coeff(fz(n),z,2); end do: a:=n-> c(n): seq(a(n), n=2..nmax);

Formula

a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7)

a(n) = 1/18*n^6+1/6*n^5+1/72*n^4-1/4*n^3-5/72*n^2+1/12*n

G.f.: (7+26*z+7*z^2)/(1-z)^7