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A013938 a(n) = Sum_{k=1..n} floor(n/k^4). 1
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

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

PROG

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

CROSSREFS

Cf. A013936, A013937.

Sequence in context: A209061 A178210 A115063 * A023809 A046100 A023757

Adjacent sequences:  A013935 A013936 A013937 * A013939 A013940 A013941

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Henri Lifchitz

STATUS

approved

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Last modified February 16 05:10 EST 2019. Contains 320140 sequences. (Running on oeis4.)