|
| |
|
|
A163920
|
|
G.f.: Sum_{k>0} k*(k+1)/2 * x^k / (1 - (-x)^k)^3.
|
|
0
| |
|
|
1, 0, 12, 9, 30, 0, 56, 60, 126, 0, 132, 126, 182, 0, 420, 316, 306, 0, 380, 330, 798, 0, 552, 888, 875, 0, 1296, 630, 870, 0, 992, 1536, 1914, 0, 2100, 1467, 1406, 0, 2652, 2360, 1722, 0, 1892, 1518, 4860, 0, 2256, 4872, 3234, 0, 4488, 2106, 2862, 0, 5060
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
FORMULA
| a(4n+2) = 0.
a(2n+1) = A034715(2n+1), where A034715 is the Dirichlet convolution of triangular numbers with themselves.
|
|
|
PROG
| (PARI) {a(n) = if( n<1, 0, polcoeff( sum(k=1, n, k*(k+1)/2 * x^k / (1 - (-x)^k)^3, x*O(x^n)), n))}
|
|
|
CROSSREFS
| Cf. A143520 (variant), A034715.
Sequence in context: A101501 A018870 A068614 * A038335 A040023 A109683
Adjacent sequences: A163917 A163918 A163919 * A163921 A163922 A163923
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Aug 06 2009
|
| |
|
|
