|
| |
|
|
A143242
|
|
Expansion of Product_{k>0} (1 - x^(9*k)) * (1-x^(9*k-2)) * (1-x^(9*k-7)) / ((1-x^(9*k-1)) * (1-x^(9*k-6)) * (1-x^(9*k-8))).
|
|
0
| |
|
|
1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, -1, 0, 1, 1, 0, 1, 1, 0, 0, -1, 0, 1, 0, 0, 1, 1, 0, -1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,1
|
|
|
COMMENTS
| |a(n)|<2 if n<156, |a(n)|<3 if n<250.
|
|
|
FORMULA
| Euler transform of period 9 sequence [ 1, -1, 1, 0, 0, 0, -1, 1, -1, ...].
G.f.: Product_{k>0} (1 - x^(9*k)) * (1-x^(9*k-2)) * (1-x^(9*k-7)) / ((1-x^(9*k-1)) * (1-x^(9*k-6)) * (1-x^(9*k-8))).
|
|
|
EXAMPLE
| 1 + q + q^3 + q^4 + q^6 + q^9 + q^12 + q^13 + q^16 + q^21 + q^24 + q^25 + ...
|
|
|
PROG
| (PARI) {a(n) = if( n<0, 0, polcoeff( prod(k=1, n, (1 - x^k)^([1, -1, 1, -1, 0, 0, 0, 1, -1][k%9 + 1]), 1 + x * O(x^n)), n))}
|
|
|
CROSSREFS
| Sequence in context: A077049 A124895 A089885 * A136442 A168030 A128431
Adjacent sequences: A143239 A143240 A143241 * A143243 A143244 A143245
|
|
|
KEYWORD
| sign
|
|
|
AUTHOR
| Michael Somos, Aug 01 2008
|
| |
|
|
