A378914 Smallest positive m such that sigma(m) does not divide n, where sigma is the sum-of-divisors function (A000203).

2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 7, 2, 2, 3, 2, 2, 3

Offset: 1

Author

Paolo Xausa, Dec 11 2024

Keywords

• nonn
• easy

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A051549, A378912.

Programs

Mathematica

A378914[n_] := Module[{m = 1}, While[Divisible[n, DivisorSigma[1,++m]]]; m];
Array[A378914, 100]

PARI

a(n) = my(m=1); while (!(n % sigma(m)), m++); m; \\ Michel Marcus, Dec 11 2024