A395045 - OEIS

A395045

Numbers k such that the greatest prime dividing arithmetic derivative of k is not larger than the greatest prime dividing k.

2, 3, 4, 5, 7, 9, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 23, 25, 26, 27, 28, 29, 31, 33, 35, 37, 38, 39, 41, 43, 44, 46, 47, 49, 50, 51, 52, 53, 54, 55, 57, 59, 61, 62, 65, 67, 68, 69, 71, 73, 74, 76, 77, 79, 81, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 97, 99, 101, 102, 103, 106, 107, 108, 109, 111, 112, 113

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

FORMULA

{k>1 such that A395042(k) <= A006530(k)}.

PROG

(PARI)

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

A006530(n) = if(n>1, vecmax(factor(n)[, 1]), 1);

is_A395045(n) = (n>1 && (A006530(A003415(n))<=A006530(n)));