%I #7 Jul 18 2019 11:36:04
%S 7,281,1602529
%N Primes of the form 3^k + 2^k + k + 1.
%C The next term is too large to include here.
%C 281 = 3^5 + 2^5 + 5 + 1,..
%C The corresponding values of k are 1, 5, 13, 905, 5341, ... ; a(5) ~ 2.016...*10^2548. - _Amiram Eldar_, Jul 18 2019
%H Amiram Eldar, <a href="/A176072/b176072.txt">Table of n, a(n) for n = 1..4</a>
%t Select[Array[3^#+2^#+#+1&,2*6! ],PrimeQ[ # ]&]
%Y Cf. A061421
%K nonn,bref
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Apr 07 2010