OFFSET
1,1
LINKS
Harry J. Smith, Table of n, a(n) for n=1..1000
EXAMPLE
All entries are themselves prime.
MATHEMATICA
Select[Range[1, 2000 ], PrimeQ[( DivisorSigma[6, # ])/DivisorSigma[2, # ]] & ]
PROG
(PARI) { n=0; for (m=1, 10^9, f=sigma(m, 6)/sigma(m, 2); if (frac(f) == 0 && isprime(f), write("b065820.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Oct 31 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Dec 06 2001
STATUS
approved