OFFSET
0,2
REFERENCES
R. C. Gunning, Lectures on Modular Forms. Princeton Univ. Press, Princeton, NJ, 1962, p. 53.
N. Koblitz, Introduction to Elliptic Curves and Modular Forms, Springer-Verlag, 1984, see p. 111.
LINKS
MAPLE
E := proc(k) local n, t1; t1 := 1-(2*k/bernoulli(k))*add(sigma[k-1](n)*q^n, n=1..60); series(t1, q, 60); end; E(14);
MATHEMATICA
terms = 16;
E14[x_] = 1 - 24*Sum[k^13*x^k/(1 - x^k), {k, 1, terms}];
E14[x] + O[x]^terms // CoefficientList[#, x]&
(* or: *)
Table[If[n == 0, 1, -24*DivisorSigma[13, n]], {n, 0, terms-1}] (* Jean-François Alcover, Feb 26 2018 *)
PROG
(PARI) a(n)=if(n<1, n==0, -24*sigma(n, 13))
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Dec 25 2000
STATUS
approved