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%I #5 Nov 21 2013 12:49:00
%S 609554401,9536162033329,5960417405949649,2328306127701998147089,
%T 355271367866755685756083382145169,
%U 29387358770557187699218413428591111182510208390715375894150039546014062887655539136439569
%N Primes of the form (5^p-3^p)/2, where prime p = Prime[A123704[n]] = A121877[n].
%C Corresponding primes p are listed in A121877[n] = Prime[A123704[n]] = {13, 19, 23, 31, 47, 127, 223, 281, 2083, ...} Numbers n such that (5^n-3^n)/2 is a prime. Numbers n such that (5^p-3^p)/2 is prime, where p = Prime[n], are listed in A123704[n] = {6, 8, 9, 11, 15, 31, 48, 60, 314, ...}.
%t Select[(5^#-3^#)/2&/@Prime[Range[50]],PrimeQ] (* _Harvey P. Dale_, Mar 30 2012 *)
%Y Cf. A123704, A121877.
%K nonn
%O 1,1
%A _Alexander Adamchuk_, Oct 08 2006