A374476 -id:A374476 - cp's OEIS frontend

A374475 Numbers k such that the least prime dividing the sum of divisors of k is equal to the least prime not dividing k.

2, 3, 5, 7, 8, 11, 13, 15, 17, 19, 21, 23, 27, 29, 31, 32, 33, 35, 37, 39, 41, 43, 45, 47, 50, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 83, 85, 87, 89, 91, 93, 95, 97, 98, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 123, 125, 127, 128, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147

Offset: 1

Graph
List
Refs
Listen
History
Text
Internal format

Antti Karttunen, Aug 06 2024

nonn

Antti Karttunen, Table of n, a(n) for n = 1..12000

Cf. A000203, A020639, A053669, A374474 (characteristic function), A374476 (composite terms).

Cf. also A370125.

A020639(n) = if(1==n,n,vecmin(factor(n)[, 1]));
A053669(n) = forprime(p=2, , if(n%p, return(p))); \\ From A053669
A374474(n) = (A020639(sigma(n))==A053669(n));
isA374475 = A374474;

cp's OEIS Frontend

A374475 Numbers k such that the least prime dividing the sum of divisors of k is equal to the least prime not dividing k.

Views

Author

Keywords

Links

Crossrefs

Programs

PARI