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A303480 Numbers k such that the average of squarefree kernels of all positive integers <= k is an integer. 3
1, 3, 4, 17, 53, 433, 456, 901, 1052, 4011, 14504, 15111, 156408, 245423, 328408, 911340, 2263141, 13736475, 20092485, 37903271, 60003559, 78733423, 84206981, 234095587, 319691535, 986119609, 1488787296, 6139123252, 8663152552, 11909530004, 19226378456, 65827587400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k such that k | A073355(k).

LINKS

Table of n, a(n) for n=1..32.

Wikipedia, Radical of an integer

EXAMPLE

3 is a term because the first 3 terms of A007947 are 1, 2 and 3 whose sum is divisible by 3.

PROG

(PARI) isok(k) = sum(i=1, k, factorback(factor(i)[, 1])) % k == 0; \\ Michel Marcus, Apr 25 2018

CROSSREFS

Cf. A007947, A073355, A226647, A284755, A285510.

Sequence in context: A115388 A187995 A296277 * A254200 A009208 A296283

Adjacent sequences:  A303477 A303478 A303479 * A303481 A303482 A303483

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Apr 24 2018

EXTENSIONS

a(13)-a(17) from Alois P. Heinz, Apr 24 2018

a(18)-a(26) from Daniel Suteu, Apr 24 2018

a(27)-a(32) from Giovanni Resta, Apr 26 2018

STATUS

approved

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Last modified December 7 09:15 EST 2021. Contains 349574 sequences. (Running on oeis4.)