OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..100
MATHEMATICA
Select[Range[2, 30000], EulerPhi[(Prime[#]+1)/2]==DivisorSigma[1, #]&] (* Harvey P. Dale, May 01 2015 *)
PROG
(PARI) for(n=2, 45000, if(eulerphi((prime(n)+1)/2)==sigma(n), print1(n, ", ")))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Mar 10 2002
STATUS
approved