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A046680 Number of divisors of n and sum of cubes of divisors of n are relatively prime. 7
1, 2, 4, 8, 9, 16, 25, 36, 81, 100, 121, 128, 144, 162, 225, 256, 289, 324, 400, 484, 512, 529, 625, 729, 841, 900, 1024, 1089, 1156, 1250, 1296, 1458, 1681, 1936, 2025, 2116, 2209, 2304, 2401, 2500, 2601, 2809, 2916, 3025, 3364, 3481, 3600, 4096, 4356, 4624 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It can be shown that this is a subset of A028982.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[5000], CoprimeQ[DivisorSigma[0, #], DivisorSigma[3, #]] &] (* Amiram Eldar, Aug 08 2019 *)

PROG

(PARI) isok(n) = gcd(numdiv(n), sigma(n, 3)) == 1; \\ Michel Marcus, Sep 24 2019

CROSSREFS

Cf. A028982, A046678, A046679, A046681, A046683, A046685.

Sequence in context: A204826 A241010 A046678 * A113570 A065391 A161792

Adjacent sequences:  A046677 A046678 A046679 * A046681 A046682 A046683

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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Last modified November 13 17:34 EST 2019. Contains 329106 sequences. (Running on oeis4.)