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A283439
Hankel transform of A033434.
0
1, -3, -9, -6, 10, 25, 15, -21, -49, -28, 36, 81, 45, -55, -121, -66, 78, 169, 91, -105, -225, -120, 136, 289, 153, -171, -361, -190, 210, 441, 231, -253, -529, -276, 300, 625, 325, -351, -729, -378, 406, 841, 435, -465, -961, -496, 528, 1089, 561, -595, -1225
OFFSET
0,2
COMMENTS
a(n) modulo 2 is A131719(n+2).
FORMULA
G.f.: (1 - 5*x + 2*x^3 - 3*x^4 + 2*x^5 - x^6)/((1 + x)*(1 - x + x^2)^3).
a(3*k) = (-1)^k*(k + 1)*(2*k + 1).
a(3*k + 1) = -(-1)^k*(k + 1)*(2*k + 3).
a(3*k + 2) = -(-1)^k*(k + 3)^2.
MATHEMATICA
CoefficientList[Series[(1 - 5*x + 2*x^3 - 3*x^4 + 2*x^5 - x^6)/((1 + x)*(1 - x + x^2)^3) , {x, 0, 35}], x] (* Indranil Ghosh, Mar 08 2017 *)
PROG
(PARI) print(Vec((1 - 5*x + 2*x^3 - 3*x^4 + 2*x^5 - x^6)/((1 + x)*(1 - x + x^2)^3) + O(x^36))); \\ Indranil Ghosh, Mar 08 2017
CROSSREFS
Sequence in context: A349403 A131954 A154593 * A134693 A096948 A224262
KEYWORD
sign,easy
AUTHOR
Paul Barry, Mar 07 2017
EXTENSIONS
More terms from Indranil Ghosh, Mar 08 2017
STATUS
approved