A216697 Numbers n such that sigma(n) mod n = 12, n is divisible by 6, but n/6 is not prime.

24, 54, 780, 2352, 430272, 184773312

Offset

1,1

Comments

Motivated by A076496 comment: if n=6p, p>3 prime, then Mod(sigma(n),n)=12. So this sequence is included in A076496, but not in A084306.

Next term > 10^11. - Donovan Johnson, Sep 27 2012

Links

Table of n, a(n) for n=1..6.

Example

sigma(24) = 60 = 2*24+12, but 24/6=4 is not prime.

Prog

(PARI) isOk(n) = { return ((n % 6 == 0) && (! isprime(n/6)) && (sigma(n) % n == 12)); }

Crossrefs

Cf. A076496, A084306.

Sequence in context: A038635 A003756 A135191 * A332541 A316361 A277108

Adjacent sequences: A216694 A216695 A216696 * A216698 A216699 A216700

Keyword

nonn

Author

Michel Marcus, Sep 15 2012

Status

approved