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%I #13 Oct 10 2012 17:53:05
%S 1,2,3,5,143,225
%N Numbers n such that 3*(2n)^(2n)+1 is prime.
%C This corresponds to the numbers such that 3m^m+1 is prime, but these must all be even, m=2n, and therefore it is more natural to record the sequence of n=m/2.
%C Next term > 15000. - _Matevz Markovic_, Oct 09 2012
%e a(1) = 1, because 2^2*3+1 = 13 is the smallest prime of this form.
%e a(2) = 2, because 4^4*3+1 = 769 is the next smallest prime of this form. a(3) = 3, because 6^6*3+1 = 139969 is again a prime.
%o (PARI) for(i=1,9999,ispseudoprime(i^i*3+1)&print1(i/2,","))
%Y Cf. A160360 (3n^n+2 is prime), A121270 = primes among Sierpinski numbers A014566(n)=n^n+1; A216148 = A216147(A110932): primes 2n^n+1; A088790, A065798.
%K hard,more,nonn
%O 1,2
%A _M. F. Hasler_, Jul 10 2009
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