OFFSET
1,1
REFERENCES
H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191. (Annotated scanned copy)
G. Loeh, Generalized Cullen primes
MATHEMATICA
Select[Range[10000], PrimeQ[# 3^# + 1] &] (* Vincenzo Librandi, Dec 02 2015 *)
PROG
(Magma) [n: n in [0..420] | IsPrime(n*3^n+1)]; // Vincenzo Librandi, Dec 02 2015
(PARI) is(n)=ispseudoprime(n*3^n+1) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(14) from Loeh link by Ray Chandler, Apr 10 2016
STATUS
approved