A292949 Subsequence of terms of A019278 whose sum of divisors is also a term of A019278.

1, 8, 15, 24, 60, 168, 512, 1023, 1536, 4092, 10752, 29127, 47360, 57120, 116508, 331520, 343976, 932064, 1556480, 1980342, 3932040, 4404480, 106151936, 238608384, 251650560, 312792480, 5099962368, 6604416000, 9623577600, 13460388480, 58350015360, 173238912000, 355744082763

Offset: 1

Author

Michel Marcus, Sep 27 2017

Keywords

• nonn

Comments

A019278 is the sequence of integers x such that sigma(sigma(x))/x is an integer.

Examples

			8 is a term since both 8 and 15=sigma(8) are terms of A019278.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..38

Crossrefs

Subsequence of A019278.

Programs

PARI

isok(n) = my(sn=sigma(n), ssn=sigma(sn)); (denominator(ssn/n)==1) && (denominator(sigma(ssn)/sn) == 1);