%I
%S 3,5,7,37,45,53,179,277,721,2087,6197,6317,8775,12781
%N Positive integers n such that n*3^n  2 is prime.
%C Similar to A060353, and to the Woodall primes, A050918. The next term in the sequence is unknown; if the sequence is infinite, the next term is greater than 5000.
%e 79 = 3*3^3  2; 1213 = 5*3^5  2; 15307 = 7*3^7  2.
%p #choose N large, then S is the desired set
%p f:=n>n*3^n  2:
%p S:={}:
%p for n from 0 to N do if(isprime(f(n))) then S:=S union {n}: fi: od
%t Select[Range[2100], PrimeQ[#*3^#  2] &] (* _Jayanta Basu_, Jun 01 2013 *)
%o PARI) for(n=1, 1e6, if(ispseudoprime(3^n*n  2), print1(n, ", "))) \\ _Altug Alkan_, Dec 01 2015
%Y Cf. A050918, A060353.
%K nonn
%O 1,1
%A _Patrick Devlin_, Apr 26 2012
%E a(11)a(14) from _Altug Alkan_, Dec 01 2015
