OFFSET
0,1
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-1,-1,2,2,2,-1,-1,-1).
FORMULA
G.f.: 6*(x^4+2*x^3+x^2+2*x+1) / ((x-1)^2*(x^2+x+1)^3). - Colin Barker, Nov 04 2014
MATHEMATICA
Differences[Table[Denominator[(n-1)^2/(n^2+n+1)], {n, 1, 50}]] (* Vaclav Kotesovec, Nov 04 2014 *)
PROG
(PARI) Vec(6*(x^4+2*x^3+x^2+2*x+1)/((x-1)^2*(x^2+x+1)^3) + O(x^100)) \\ Colin Barker, Nov 04 2014
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Dec 20 2008
EXTENSIONS
Edited by N. J. A. Sloane, Dec 20 2008
More terms from Colin Barker, Nov 04 2014
STATUS
approved