A141231 - OEIS

A141231

Positive integers whose prime factorizations contain only primes from A001122.

3, 5, 9, 11, 13, 15, 19, 25, 27, 29, 33, 37, 39, 45, 53, 55, 57, 59, 61, 65, 67, 75, 81, 83, 87, 95, 99, 101, 107, 111, 117, 121, 125, 131, 135, 139, 143, 145, 149, 159, 163, 165, 169, 171, 173, 177, 179, 181, 183, 185, 195, 197, 201, 209, 211, 225, 227, 243, 247, 249

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..60.

MATHEMATICA

aQ[n_] := Length[Select[FactorInteger[n][[;; , 1]], # > 1 && PrimitiveRoot@# != 2 &]] == 0; Select[Range[2, 250], aQ] (* Amiram Eldar, Dec 09 2018 *)

PROG

(PARI) isokp(p) = znorder(Mod(2, p))==(p-1);

isok(n) = {if ((n>1) && (n % 2), my(f=factor(n)); #select(x->isokp(x), f[, 1]) == #f~; , 0); } \\ Michel Marcus, Dec 09 2018

CROSSREFS

Cf. A001122, A000040.