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

1,2

Comments

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

Links

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

Example

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

Prog

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

Crossrefs

Subsequence of A019278.

Sequence in context: A034114 A069826 A129076 * A072177 A169875 A318111

Adjacent sequences: A292946 A292947 A292948 * A292950 A292951 A292952

Keyword

nonn

Author

Michel Marcus, Sep 27 2017

Status

approved