OFFSET
0,3
LINKS
Index entries for linear recurrences with constant coefficients, signature (3,-2,-2,3,-1).
FORMULA
a(n) = (1+(-1)^n+n-n^2+2*n^3)/2. G.f.: (1-2*x+7*x^2+4*x^3+2*x^4)/((1-x)^4*(1+x)). [Colin Barker, Sep 10 2012]
MATHEMATICA
f[n_]:= If[Mod[n, 2] == 0, n^3 + 1, n^3]; Table[f[n] - n*(n - 1)/2, {n, 0, 40}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula, Jun 10 2007
EXTENSIONS
Edited, corrected and extended by Stefan Steinerberger, Jul 21 2007
STATUS
approved