A162012 The sequence of the absolute values of the a(n-2) coefficients of A162011.

0, 19, 663, 6501, 36729, 149842, 491274, 1375206, 3413982, 7710813, 16133689, 31690659, 59028879, 105082068, 179893252, 297641916, 477906924, 747198807, 1140797259, 1704931921, 2499346773, 3600290694, 5103978990, 7130572930

Offset: 1

Author

Johannes W. Meijer, Jun 27 2009

Keywords

• easy
• nonn

Crossrefs

Equals the absolute values of the coefficients that precede the a(n-2) factors of the recurrence relations RR(n) of A162011.

Cf. A006324 [a(n-1)] and A162013 [a(n-3)].

Programs

Maple

nmax:=26; for n from 1 to nmax do RR(n) := expand(product((1-(2*k-1)^2*z)^(n-k+1),k=1..n),z) od: T:=1: for n from 1 to nmax do a(T):=coeff(RR(n),z,2): T:=T+1 od: seq(a(k),k=1..T-1);

Formula

a(n) = (20*n^8+80*n^7+4*n^6-268*n^5-155*n^4+230*n^3+131*n^2-42*n)/360

Recurrence relation sum((-1)^k*binomial(9,k)*a(n-k), k= 0 .. 9) = 0

GF(z) = z*(19+492*z+1218*z^2+492*z^3+19*z^4)/(1-z)^9