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

2,1

Comments

See A157702 for background information.

Links

Table of n, a(n) for n=2..27.

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

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);

Crossrefs

Cf. A156921, A157702.

Sequence in context: A326221 A197091 A174243 * A197763 A202251 A365841

Adjacent sequences: A157703 A157704 A157705 * A157707 A157708 A157709

Keyword

easy,nonn

Author

Johannes W. Meijer, Mar 07 2009

Status

approved