A070310 Numbers n such that the sum of its aliquot parts and the number of its divisors are both perfect numbers.

28, 652, 10828

Offset: 1

Author

Jason Earls, May 10 2002

Keywords

• more
• nonn
• bref

Comments

Subsequence of A237286. - Roderick MacPhee, Jan 19 2017

Crossrefs

Cf. A000396, A001065, A000005.

Programs

Mathematica

p = {6, 28, 496, 8128, 33550336}; Do[a = Divisors[n]; If[ Position[p, Plus @@ Drop[a, -1]] != {} && Position[p, Length[a]] != {}, Print[n]], {n, 1, 10^7}]

PARI

{for(n=1,10^8,d=numdiv(n); if(d==sigma(d)-d,s=sigma(n)-n; if(s==sigma(s)-s,print1(n,","))))}

Extensions

Edited by Robert G. Wilson v, May 14 2002

No further terms below 10^8. Is the sequence complete? - Klaus Brockhaus, May 17 2002