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A173247
a(0) = -1 and a(n) = (-1)^n*(n - 4 - 3*n^2)/2 for n >= 1.
1
-1, 3, -7, 14, -24, 37, -53, 72, -94, 119, -147, 178, -212, 249, -289, 332, -378, 427, -479, 534, -592, 653, -717, 784, -854, 927, -1003, 1082, -1164, 1249, -1337, 1428, -1522, 1619, -1719, 1822, -1928, 2037, -2149, 2264, -2382, 2503, -2627, 2754
OFFSET
0,2
FORMULA
G.f.: (x^3 - x^2 - 1)/(x + 1)^3.
a(n) = -3*a(n-1) -3*a(n-2) -a(n-3).
From Franck Maminirina Ramaharo, Dec 27 2018: (Start)
a(n) = (A143689(n) + 1)*(-1)^(n + 1), n >= 1.
E.g.f.: 1 - (1/2)*(4 - 2*x + 3*x^2)*exp(-x). (End)
MATHEMATICA
p[x_] = (x^3 - x^2 - 1)/(x + 1)^3;
a = Table[SeriesCoefficient[ Series[p[x], {x, 0, 50}], n], {n, 0, 50}]
PROG
(Magma) [-1] cat [(-1)^n*(n-4-3*n^2)/2: n in [1..50]]; // Vincenzo Librandi, Apr 20 2015
(PARI) Vec((x^3 - x^2 - 1)/(x + 1)^3 + O(x^50)) \\ Michel Marcus, Apr 20 2015
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Roger L. Bagula, Feb 13 2010
EXTENSIONS
Definition simplified by the Assoc. Editors of the OEIS, Feb 21 2010
Incorrect comment removed by Joerg Arndt, Dec 27 2018
STATUS
approved