A171127 Numbers k such that A169611(k) = 2.

4, 6, 9, 20, 28, 30, 42, 44, 45, 52, 63, 66, 68, 76, 78, 92, 99, 100, 102, 114, 116, 117, 124, 138, 140, 148, 150, 153, 164, 171, 172, 174, 186, 188, 196, 207, 210, 212, 220, 222, 225, 236, 244, 246, 258, 260, 261, 268, 279, 282, 284, 292, 294, 308, 315, 316

Offset

1,1

Comments

The asymptotic density of this sequence is 19/108. - 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@ 317, f@# == 2 &] (* Robert G. Wilson v, Dec 19 2009) (* Extended beyond 150 by R. J. Mathar, Dec 09 2009 *)

Crossrefs

Cf. A169611.

Sequence in context: A220144 A346591 A152002 * A098485 A293399 A120712

Adjacent sequences: A171124 A171125 A171126 * A171128 A171129 A171130

Keyword

nonn

Author

Juri-Stepan Gerasimov, Dec 04 2009

Extensions

Extended beyond 150 by R. J. Mathar, Dec 09 2009

Status

approved