OFFSET
1,1
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
MATHEMATICA
f[n_] := Block[ {a = FactorInteger[n], k = l = s = 1}, l = Length[a]; While[k <= l, s = s * (a[[k, 1]]^a[[k, 2]] + 1); k++ ]; Return[s]]; Select[ Range[200], PrimeQ[ f[ # ] - 1] & ]
PROG
(PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) } { n=0; for (m=1, 10^9, if (isprime(usigma(m) - 1), write("b065872.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Nov 02 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Dec 07 2001
STATUS
approved