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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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
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
Sequence in context: A227841 A225256 A093523 * A123386 A060999 A089187
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

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Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)