A157708 The z^2 coefficients of the polynomials in the GF4 denominators of A156933

18, 254, 1571, 6335, 19615, 50743, 115234, 237066, 451320, 807180, 1371293, 2231489, 3500861, 5322205, 7872820, 11369668, 16074894, 22301706, 30420615, 40866035, 54143243, 70835699, 91612726

Offset

1,1

Comments

See A157705 for background information.

Links

Table of n, a(n) for n=1..23.

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) = 1/2*n^6+5/2*n^5+41/8*n^4+67/12*n^3+27/8*n^2+11/12*n

G.f.: (18 + 128*z + 171*z^2 + 42*z^3 + z^4)/(1-z)^7

Maple

nmax:=23; for n from 0 to nmax do fz(n):=product((1-(2*n+1-2*k)*z)^(3*k+1), k=0..n); c(n):= coeff(fz(n), z, 2); end do: a:=n-> c(n): seq(a(n), n=1..nmax);

Crossrefs

Cf. A156933, A157705

Sequence in context: A255371 A016175 A062141 * A159537 A136660 A362808

Adjacent sequences: A157705 A157706 A157707 * A157709 A157710 A157711

Keyword

easy,nonn

Author

Johannes W. Meijer, Mar 07 2009

Status

approved