A339879 Numbers k for which k-1 is a multiple of A053575(k) [the odd part of phi(k)].

1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 19, 20, 23, 24, 28, 29, 30, 31, 32, 34, 37, 40, 41, 43, 47, 48, 51, 52, 53, 59, 60, 61, 64, 66, 67, 68, 70, 71, 73, 79, 80, 83, 85, 89, 91, 96, 97, 101, 102, 103, 107, 109, 112, 113, 120, 127, 128, 130, 131, 136, 137, 139, 149, 151, 157, 160, 163, 167, 170, 173, 176, 179

Offset: 1

Author

Antti Karttunen, Dec 24 2020

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..12855

Crossrefs

Cf. A000010, A000265, A053575.

Subsequences: A000040, and A339880 (odd composite terms), A339869, A339870.

Cf. also comments in A339817.

Programs

PARI

A000265(n) = (n>>valuation(n, 2));
isA339879(n) = !((n-1)%A000265(eulerphi(n)));