A286228 Numbers n such that d(n) = 2^omega(n) + omega(n) where d = A000005 and omega = A001221.

1, 4, 9, 12, 18, 20, 25, 28, 44, 45, 49, 50, 52, 63, 68, 75, 76, 92, 98, 99, 116, 117, 121, 124, 147, 148, 153, 164, 169, 171, 172, 175, 188, 207, 212, 236, 242, 244, 245, 261, 268, 275, 279, 284, 289, 292, 316, 325, 332, 333, 338, 356, 361, 363, 369, 387, 388, 404, 412, 423, 425, 428

Offset

1,2

Links

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

Example

1 is in this sequence because d(1) = 1 is equal to 2^omega(1) + omega(1) = 2^0 + 0 = 1.

Mathematica

Select[Range@ 432, Function[f, DivisorSigma[0, #] == 2^f + f]@ PrimeNu@ # &] (* Michael De Vlieger, May 04 2017 *)

Prog

(PARI) isok(n) = numdiv(n) == 2^omega(n) + omega(n); \\ Michel Marcus, May 07 2017

Crossrefs

Supersequence of A001248 and of A054753.

Cf. A006127.

Sequence in context: A067259 A349931 A060687 * A312863 A312864 A326071

Adjacent sequences: A286225 A286226 A286227 * A286229 A286230 A286231

Keyword

nonn

Author

Juri-Stepan Gerasimov, May 04 2017

Status

approved