A259305 Numbers n such that there exists an x!=n that makes {x,x,x,n} an amicable multiset.

756000, 1220940, 1437480, 1973160, 5019840, 9058140, 9703260, 11058480, 11641680, 13085280, 17089920, 18117000, 19370880, 21282912, 21628080, 25295760, 25585560, 26936640, 27763560, 28191240, 29104200, 29203020, 30450420, 32839560, 33279120, 33398820

Offset: 1

Author

Jeppe Stig Nielsen, Jun 23 2015

Keywords

• nonn

Comments

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

For the x values, see A259304.

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, A259304, A259302, A259303, A259306, A036471.

Programs

PARI

isOK(n) = x=(sigma(n)-n)/3; x>0&x!=n&denominator(x)==1&sigma(x)==3*x+n