A378915 Positive integers k such that k is not divisible by sigma(m) for any m >= 2, where sigma is the sum-of-divisors function (A000203).

1, 2, 5, 10, 11, 17, 19, 22, 23, 25, 29, 34, 37, 41, 43, 46, 47, 50, 53, 55, 58, 59, 61, 67, 71, 73, 79, 82, 83, 85, 86, 89, 94, 95, 97, 101, 103, 106, 107, 109, 113, 115, 118, 122, 125, 131, 134, 137, 139, 142, 145, 146, 149, 151, 157, 163, 166, 167, 170, 173

Offset

1,2

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sigma(n)

Mathematica

With[{upto = 500}, Table[If[Count[Divisible[n, #[[;; n]]], True] == 1, n, Nothing], {n, upto}] & [DivisorSigma[1, Range[upto]]]]

Prog

(PARI) isok(m) = for(k=2, m, if (!(m % sigma(k)), return(0))); 1; \\ Michel Marcus, Dec 12 2024

Crossrefs

Positions of ones in A378913.

Cf. A000203.

Sequence in context: A353356 A363890 A257031 * A167799 A179871 A258116

Adjacent sequences: A378912 A378913 A378914 * A378919 A378920 A378922

Keyword

nonn,new

Author

Paolo Xausa, Dec 11 2024

Status

approved