A177204 Pseudoperfect totient numbers (A288452) which are not powers of primes (A000961).

15, 33, 35, 39, 51, 55, 65, 69, 77, 85, 87, 111, 115, 119, 123, 141, 143, 153, 155, 159, 161, 175, 177, 183, 187, 201, 205, 209, 213, 219, 221, 235, 245, 247, 249, 253, 255, 265, 267, 287, 291, 295, 299, 303, 305, 309, 319, 321, 323, 325, 327, 329, 339, 341, 363, 371, 377, 391, 393, 403, 407, 411, 413, 415

Offset

1,1

Comments

A proper subset of A288452. All odd primes and all powers of 3 are pseudoperfect totient numbers. First term which has k factors counting multiplicity >1: 15, 153, 875, 4375, 62451, etc. First term which has k distinct factors >1: 15, 255, 21505, etc.

Links

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

Mathematica

fQ[n_] := Module[{tots = Rest@ NestWhileList[ EulerPhi, n, # > 1 &]}, MemberQ[Total /@ Subsets[tots, Length[ tots]], n]]; Select[ Range[ 3, 440, 2], fQ@# && !PrimePowerQ@# &]

Crossrefs

Cf. A288452, A000961.

Sequence in context: A331551 A180815 A336625 * A342193 A343338 A302697

Adjacent sequences: A177201 A177202 A177203 * A177205 A177206 A177207

Keyword

nonn,easy

Author

Amiram Eldar and Robert G. Wilson v, Jul 02 2017

Status

approved