A259304 Numbers n such that there exists an x!=n that makes {n,n,n,x} an amicable multiset.

796320, 1205820, 1277640, 1963080, 5154240, 8599500, 8694000, 9022860, 10820880, 12149280, 15845760, 17173800, 18023040, 19323360, 21360240, 22720320, 25494480, 27052200, 27335880, 28365480, 28574280, 28704060, 29211000, 30329640, 30373200, 30450420, 31433220

Offset: 1

Author

Jeppe Stig Nielsen, Jun 23 2015

Keywords

• nonn

Comments

We call the multiset {n,n,n,x} amicable iff sigma(n)=sigma(x)=n+n+n+x.

For the x values, see A259305.

If the condition x!=n were dropped, the terms from A027687 would also belong here.

Links

• John Cerkan, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A027687, A259307, A259305, A259302, A259303, A259306, A036471.

Programs

PARI

isOK(n) = x=sigma(n)-3*n; x>0&x!=n&sigma(x)==3*n+x