login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A161802
G.f. is Q_1(q) where q*Q_1(q^4) is a series quadrisection of the g.f. of A161800.
2
2, -16, 18, 176, -544, -160, 2834, -5104, 3232, 18032, -68992, 48400, 143074, -343088, 461344, 63888, -2298880, 2963520, 1387424, -5145536, 10416514, -9297312, -31084704, 42991712, 34760672, -51170800, 81567168, -94111088
OFFSET
0,1
COMMENTS
The g.f. of A161800 has two nonzero series quadrisections; the other is given by A161801.
EXAMPLE
G.f.: Q_1(q) = 2 - 16*q + 18*q^2 + 176*q^3 - 544*q^4 - 160*q^5 + 2834*q^6 +...
PROG
(PARI) {a(n)=local(L=sum(m=1, 4*n+1, 2*2^valuation(m, 2)*sumdiv(m, d, -(-1)^d*d)*x^m/m)+x*O(x^(4*n+1))); polcoeff(exp(L), 4*n+1)}
CROSSREFS
Sequence in context: A058242 A101075 A022370 * A323193 A050850 A082475
KEYWORD
sign
AUTHOR
Paul D. Hanna, Jul 19 2009
STATUS
approved