OFFSET
1,2
LINKS
William A. Stein, Dimensions of the spaces S_k(Gamma_0(N)).
William A. Stein, The modular forms database
FORMULA
Conjecture: a(n) = 4*(n-1)-2*floor((n-1)/3) for n > 1. - Wesley Ivan Hurt, Dec 27 2016
Conjectures from Colin Barker, Jun 09 2019: (Start)
G.f.: x*(1 + 3*x + 4*x^2 + x^3 + x^4) / ((1 - x)^2*(1 + x + x^2)).
a(n) = a(n-1) + a(n-3) - a(n-4) for n>5.
(End)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 08 2001
STATUS
approved