OFFSET
1,2
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000
EXAMPLE
The proper divisors of 56 are {1, 2, 4, 7, 8, 14, 28}. 1*2*4*7*8*14*28 = 175616 = 56^3. 1+2+4+7+8+14+28 = 64 = 4^3. Since both the product of proper divisors and the sum of proper divisors are cubes, 56 is a member of this sequence.
PROG
(PARI) for(n=1, 10^7, d=divisors(n); s=sum(i=1, #d-1, d[i]); p=prod(j=1, #d-1, d[j]); if((p!=1||s!=1), if(ispower(s, 3)&&ispower(p, 3), print1(n, ", "))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Derek Orr, Jun 27 2014
STATUS
approved