%I

%S 2,3,5,181,40087,251737

%N Primes p such that gcd(p, prime(p)^2 - 1) does not equal 1.

%C No further terms up to 41161739. - _Harvey P. Dale_, Dec 23 2011

%e 5 belongs in the sequence because gcd(5, P_5^2 -1) = gcd(5, 120) = 5.

%t Do[ If[ GCD[ Prime[n], Prime[ Prime[n]]^2 - 1] != 1, Print[ Prime[n]] ], {n, 1, 10^6} ]

%Y Cf. A064830.

%K nonn,more

%O 1,1

%A _Robert G. Wilson v_, Oct 26 2001