A046678 Number of divisors of n and sum of divisors of n are relatively prime.

1, 2, 4, 8, 9, 16, 25, 36, 64, 81, 100, 121, 128, 144, 162, 225, 256, 289, 324, 400, 484, 512, 529, 576, 625, 729, 841, 900, 1024, 1089, 1156, 1250, 1296, 1458, 1600, 1681, 1936, 2025, 2116, 2209, 2304, 2401, 2500, 2601, 2809, 3025, 3364, 3481

Offset

1,2

Comments

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

Links

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

Mathematica

Select[Range[3490], CoprimeQ[DivisorSigma[1, #], DivisorSigma[0, #]] &] (* Jayanta Basu, Jun 27 2013 *)

Prog

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

Crossrefs

Cf. A000005, A000203, A028982, A046679, A046680, A046681, A046683, A046685.

Sequence in context: A241010 A354956 A348825 * A330606 A046680 A331992

Adjacent sequences: A046675 A046676 A046677 * A046679 A046680 A046681

Keyword

nonn

Author

Labos Elemer

Status

approved