OFFSET
0,3
REFERENCES
G. van der Geer, Hilbert Modular Surfaces, Springer-Verlag, 1988; p. 188.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,-1,1,-2,1).
FORMULA
a(n) = 2 + floor(n*(n - 1)/3), for n>=2, with a(0)=1, a(1)=1. - G. C. Greubel, Dec 20 2017
MATHEMATICA
CoefficientList[Series[(1 - x^6) (1 - x^8)/((1 - x) (1 - x^2) (1 - x^3)^2 (1 - x^4)), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 29 2014 *)
Join[{1, 1}, LinearRecurrence[{2, -1, 1, -2, 1}, {2, 4, 6, 8, 12}, 30]] (* or *) Join[{1, 1}, Table[2 + Floor[n*(n-1)/3], {n, 2, 30}]] (* G. C. Greubel, Dec 20 2017 *)
PROG
(PARI) a(n)=n*(n-1)\3+2-(n<2) \\ Tani Akinari, Jun 27 2014
(PARI) Vec((1-x^6)*(1-x^8)/((1-x)*(1-x^2)*(1-x^3)^2*(1-x^4)) + O(x^100)) \\ Michel Marcus, Jun 28 2014
(PARI) for(n=0, 30, print1(if(n==0, 1, if(n==1, 1, 2 + floor(n*(n-1)/3))), ", ")) \\ G. C. Greubel, Dec 20 2017
(Magma) [1, 1] cat [2 + Floor(n*(n-1)/3): n in [2..30]]; // G. C. Greubel, Dec 20 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 05 2004
STATUS
approved