OFFSET
0,3
REFERENCES
Turner, Zachary J., Bryson W. Finklea, and Terri Moore. "Combinatorial Approaches to Minimal Zero Sequences of Finite Abelian Groups, and a Surprising Connection." Preprint, Jan 09 2004.
LINKS
Colin Barker, Table of n, a(n) for n = 0..650
Index entries for linear recurrences with constant coefficients, signature (40,-390,1080,-729).
FORMULA
From Chai Wah Wu, Aug 09 2016: (Start)
a(n) = 40*a(n-1) - 390*a(n-2) + 1080*a(n-3) - 729*a(n-4) for n > 3.
G.f.: x^2*(-180*x + 24)/((x - 1)*(3*x - 1)*(9*x - 1)*(27*x - 1)). (End)
a(n) = (9-3^(2+n)-9^n+27^n)/24. - Colin Barker, Aug 10 2016
MATHEMATICA
Table[(3^n - 1) (3^n - 3) (3^n + 3)/4!, {n, 0, 18}] (* or *)
CoefficientList[Series[x^2 (-180 x + 24)/((x - 1) (3 x - 1) (9 x - 1) (27 x - 1)), {x, 0, 18}], x] (* Michael De Vlieger, Aug 11 2016 *)
Table[(Times@@(3^n+{-3, -1, 3}))/24, {n, 0, 20}] (* or *) LinearRecurrence[{40, -390, 1080, -729}, {0, 0, 24, 780}, 20] (* Harvey P. Dale, Dec 11 2022 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Aug 09 2016
STATUS
approved