A328393 Numbers whose arithmetic derivative (A003415) is a squarefree number (A005117).

2, 3, 5, 6, 7, 9, 10, 11, 13, 17, 18, 19, 21, 22, 23, 25, 26, 29, 30, 31, 33, 34, 37, 38, 41, 42, 43, 45, 47, 49, 53, 57, 58, 59, 61, 62, 63, 66, 67, 69, 70, 71, 73, 74, 75, 78, 79, 82, 83, 85, 89, 90, 93, 97, 98, 101, 102, 103, 105, 106, 107, 109, 110, 113, 114, 117, 118, 121, 126, 127, 129, 130, 131, 133, 134, 137, 139, 142

Offset: 1

Author

Antti Karttunen, Oct 19 2019

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Union of A000040 and A328234. Complement of A328303.

Cf. A005117, A008966, A003415.

Cf. A328252 (nonsquarefree terms), A157037, A192192, A327978 (other subsequences).

Programs

PARI

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
isA328393(n) = issquarefree(A003415(n));