OFFSET
2,2
COMMENTS
Conjecture: a(n) = 18n - 41 for n > 2. - Peter Luschny, Mar 04 2012
LINKS
William A. Stein, Dimensions of the spaces S_k^{new}(Gamma_1(N))
William A. Stein, The modular forms database
Index entries for linear recurrences with constant coefficients, signature (2, -1).
FORMULA
a(n) = 2*a(n-1)-a(n-2) for n>4. G.f.: x^2*(-1+15*x+4*x^2)/(1-x)^2. [Colin Barker, Sep 28 2012]
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Jul 14 2001
STATUS
approved