OFFSET
1,5
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
n=17: sigma(17) = 18, 2^18 = 262144, 262144 mod 17 = 4 = a(17).
MATHEMATICA
Table[PowerMod[2, DivisorSigma[1, n], n], {n, 90}] (* Harvey P. Dale, Jun 23 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Aug 16 2002
STATUS
approved