OFFSET
0,9
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -2, 1).
FORMULA
G.f.: x^6(1-x^3+x^5+x^11-x^13+x^16)(1-x^6)/((1-x)(1-x^2)(1-x^3)(1-x^27)).
a(n)= +2*a(n-1) -a(n-2) +a(n-27) -2*a(n-28) +a(n-29). - R. J. Mathar, Aug 11 2021
MAPLE
MATHEMATICA
Table[Floor[n*(n - 1)/27], {n, 0, 5!}] (* Vladimir Joseph Stephan Orlovsky, Mar 14 2010 *)
CoefficientList[Series[x^6 (1 - x^3 + x^5 + x^11 - x^13 + x^16) (1 - x^6)/((1 - x) (1 - x^2) (1 - x^3) (1 - x^27)), {x, 0, 70}], x] (* Vincenzo Librandi, Mar 28 2014 *)
PROG
(PARI) a(n)=(n^2-n)\27
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Typo in Mathematica program fixed by Vincenzo Librandi, Mar 28 2014
STATUS
approved