A171126 - OEIS

A171126

Numbers k such that A169611(k) = 1.

2, 3, 10, 14, 15, 21, 22, 26, 33, 34, 38, 39, 46, 50, 51, 57, 58, 62, 69, 70, 74, 75, 82, 86, 87, 93, 94, 98, 105, 106, 110, 111, 118, 122, 123, 129, 130, 134, 141, 142, 146, 147, 154, 158, 159, 165, 166, 170, 177, 178, 182, 183, 190, 194, 195, 201, 202, 206, 213

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OFFSET

1,1

COMMENTS

Appears to be numbers k such that tau(36*k) = 2*tau(6*k). - Gary Detlefs, Jan 13 2020

The asymptotic density of this sequence is 5/18. - Amiram Eldar, Jan 16 2022

LINKS

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

MATHEMATICA

f[n_] := Plus @@ Last /@ Select[ FactorInteger@ n, 1 < #[[1]] < 4 &]; Select[ Range@ 213, f@# == 1 &] (* Robert G. Wilson v, Dec 19 2009 *)

PROG

(PARI) isok(n) = valuation(n, 2)+valuation(n, 3) == 1; \\ Michel Marcus, Jan 13 2020