%I M2699 #17 Apr 08 2019 03:07:11
%S 1,3,7,33,67,223,663,912,1383,3777,3972,10669,48375
%N Numbers k such that k*4^k + 1 is prime.
%D H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H G. Loeh, <a href="http://guenter.loeh.name/gc/status.html">Generalized Cullen primes</a>
%o (PARI) is(n)=ispseudoprime(n*4^n+1) \\ _Charles R Greathouse IV_, Feb 17 2017
%K hard,nonn
%O 1,2
%A _N. J. A. Sloane_
%E More terms from _Robert G. Wilson v_
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008