OFFSET
0,1
REFERENCES
J.-P. Serre, Course in Arithmetic, Chap. VII, Section 4.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: 77683 - 552 * Sum_{i>=1} sigma_21(i)q^i where sigma_21(n) is A013969.
MATHEMATICA
terms = 15;
E22[x_] = 77683 - 552*Sum[k^21*x^k/(1 - x^k), {k, 1, terms}];
E22[x] + O[x]^terms // CoefficientList[#, x]& (* Jean-François Alcover, Feb 26 2018 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Dec 22 2016
STATUS
approved