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A123363
a(n) = n^3 + (-1)^(n+1).
1
-1, 2, 7, 28, 63, 126, 215, 344, 511, 730, 999, 1332, 1727, 2198, 2743, 3376, 4095, 4914, 5831, 6860, 7999, 9262, 10647, 12168, 13823, 15626, 17575, 19684, 21951, 24390, 26999, 29792, 32767, 35938, 39303, 42876, 46655, 50654, 54871, 59320, 63999
OFFSET
0,2
FORMULA
G.f.: ( -1+5*x-x^2+9*x^3 ) / ( (1+x)*(x-1)^4 ). - R. J. Mathar, Aug 06 2012
E.g.f.: x*(1 + 3*x + x^2)*exp(x) - exp(-x). - G. C. Greubel, Oct 12 2017
MATHEMATICA
CoefficientList[Series[(-1 + 5*x - x^2 + 9*x^3)/((1 + x)*(x - 1)^4), {x, 0, 50}], x] (* G. C. Greubel, Oct 12 2017 *)
PROG
(PARI) for(n=0, 50, print1(n^3 + (-1)^(n+1), ", ")) \\ G. C. Greubel, Oct 12 2017
(Magma) [n^3 + (-1)^(n+1): n in [0..50]]; // G. C. Greubel, Oct 12 2017
CROSSREFS
Sequence in context: A137108 A294128 A099815 * A102961 A155581 A349329
KEYWORD
sign,easy
AUTHOR
Chenxing (cxwind(AT)gmail.com), Oct 12 2006
EXTENSIONS
Corrected and extended by N. J. A. Sloane, Oct 14 2006
STATUS
approved