A348506 Numbers k such that sigma(k) is a multiple of usigma(k), where sigma is the sum of divisors function, A000203, and usigma is the unitary sigma, A034448.

1, 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 26, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 55, 57, 58, 59, 61, 62, 65, 66, 67, 69, 70, 71, 73, 74, 77, 78, 79, 82, 83, 85, 86, 87, 89, 91, 93, 94, 95, 97, 101, 102, 103, 105, 106, 107, 108, 109, 110, 111, 113, 114, 115, 118, 119

Offset: 1

Author

Antti Karttunen, Oct 29 2021

Keywords

• nonn

Comments

Conjectured to be the union of A005117 and A063880.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000

Crossrefs

Positions of ones in A348505.

Cf. A005117 and A063880.

Cf. A000203, A034448.

Programs

PARI

A034448(n) = { my(f=factorint(n)); prod(k=1, #f~, 1+(f[k, 1]^f[k, 2])); }; \\ After code in A034448
isA348506(n) = !(sigma(n)%A034448(n));