A259306 Numbers n such that there exists an x!=n that makes {n,n,x,x} an amicable multiset.

1441440, 1860768, 3205440, 3378240, 3423420, 3914820, 4029480, 4437720, 5738040, 6093360, 6807240, 7136640, 7239120, 7551360, 9402120, 10204740, 12270720, 12405120, 12942720, 13495680, 14627340, 14725620, 15233400, 17166240, 18097800, 19158048, 23023440

Offset

1,1

Comments

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

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

Prog

(PARI) isOK(n) = x=(sigma(n)-2*n)/2; x>0 && x!=n && denominator(x)==1 && sigma(x)==n+n+x+x

Crossrefs

Cf. A027687, A259307, A259302, A259303, A259304, A259305, A036471.

Sequence in context: A339477 A234657 A015361 * A210629 A156621 A108841

Adjacent sequences: A259303 A259304 A259305 * A259307 A259308 A259309

Keyword

nonn

Author

Jeppe Stig Nielsen, Jun 23 2015

Status

approved