OFFSET
1,4
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
William A. Stein, Dimensions of the spaces S_k^{new}(Gamma_0(N))
William A. Stein, The modular forms database
Index entries for linear recurrences with constant coefficients, signature (0,1,1,0,-1).
FORMULA
From Colin Barker, Sep 27 2012: (Start)
a(n) = a(n-2) + a(n-3) - a(n-5) for n > 5.
G.f.: x^2*(1 + x + 2*x^2 + x^3)/((1 - x)^2*(1 + x)*(1 + x + x^2)).
(End)
a(n) = n-1 - floor((n-1)/2) + floor((n-1)/3). - Ridouane Oudra, Oct 15 2020
MATHEMATICA
Rest@ CoefficientList[Series[x^2*(1 + x + 2*x^2 + x^3)/((1 - x)^2*(1 + x)*(1 + x + x^2)), {x, 0, 69}], x] (* or *)
Array[# - Floor[#/2] + Floor[#/3] &[# - 1] &, 69] (* Michael De Vlieger, Oct 15 2020 *)
PROG
(PARI) concat(0, Vec(x^2*(1 +x +2*x^2 +x^3)/((1 -x)^2*(1 +x)*(1 +x +x^2)) + O(x^80))) \\ Michel Marcus, Oct 15 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 10 2001
STATUS
approved