A063784 Primes that are the sum of cubes of divisors of an integer.

73, 757, 1772893, 48551233240513, 378890487846991, 3156404483062657, 17390284913300671, 280343912759041771, 319913861581383373, 487014306953858713, 7824668707707203971, 8443914727229480773

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Formula

Primes of form p = sigma(3, x).

Example

sigma(3,9) = 1 + 27 + 729 = 757, a prime.

Prog

(PARI) { n=0; p=0; for (m=1, 10^9, p=nextprime(p+1); if(isprime(q=p^6 + p^3 + 1), write("b063784.txt", n++, " ", q); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 31 2009

Crossrefs

Cf. A001158, A023194.

Sequence in context: A133753 A177514 A137835 * A066101 A272768 A100412

Adjacent sequences: A063781 A063782 A063783 * A063785 A063786 A063787

Keyword

nonn

Author

Labos Elemer, Aug 17 2001

Status

approved