A350317 Totient numbers k such that 5*k is a nontotient.

1, 10, 18, 46, 58, 70, 78, 82, 102, 106, 110, 130, 136, 148, 166, 178, 190, 220, 222, 226, 238, 250, 262, 268, 270, 282, 292, 310, 316, 330, 342, 346, 358, 378, 382, 418, 430, 438, 442, 466, 478, 486, 490, 498, 502, 508, 522, 556, 562, 568, 586, 598, 606, 618

Offset

1,2

Links

Winston de Greef, Table of n, a(n) for n = 1..10000

Example

10 is a term since 10 = phi(11) = phi(22), but phi(n) = 5*10 = 50 has no solution.
18 is a term since 18 = phi(19) = phi(27) = phi(38) = phi(54), but phi(n) = 5*18 = 90 has no solution.

Prog

(PARI) isA350317(n) = istotient(n) && !istotient(5*n)

Crossrefs

Totient numbers k such that m*k is a nontotient: A350316 (m=3), this sequence (m=5), A350318 (m=7), A350319 (m=9), A350320 (m=10), A350321 (m=14).

Cf. A002202, A005277.

Sequence in context: A007937 A300601 A301326 * A255603 A291931 A050576

Adjacent sequences: A350314 A350315 A350316 * A350318 A350319 A350320

Keyword

nonn

Author

Jianing Song, Dec 24 2021

Status

approved