1,2

Table of n, a(n) for n=1..57.

G.f.: (1/(1 - x))*Sum_{k>=1} x^(k^4)/(1 - x^(k^4)). - Ilya Gutkovskiy, Feb 11 2017

(PARI) a(n) = sum(k=1, n, n\k^4); \\ Michel Marcus, Feb 11 2017

Cf. A013936, A013937.

Sequence in context: A209061 A178210 A115063 * A023809 A046100 A023757

Adjacent sequences: A013935 A013936 A013937 * A013939 A013940 A013941

nonn

N. J. A. Sloane, Henri Lifchitz

approved