

A007646


Numbers n such that n*4^n + 1 is prime.
(Formerly M2699)


5



1, 3, 7, 33, 67, 223, 663, 912, 1383, 3777, 3972, 10669, 48375
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OFFSET

1,2


REFERENCES

H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190191.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..13.
G. Loeh, Generalized Cullen primes


PROG

(PARI) is(n)=ispseudoprime(n*4^n+1) \\ Charles R Greathouse IV, Feb 17 2017


CROSSREFS

Sequence in context: A089622 A241147 A143967 * A238314 A120566 A057480
Adjacent sequences: A007643 A007644 A007645 * A007647 A007648 A007649


KEYWORD

hard,nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Robert G. Wilson v
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008


STATUS

approved



