

A002257


Numbers n such that 13*4^n + 1 is prime.
(Formerly M3247 N1310)


1



1, 4, 5, 10, 14, 41, 94, 154, 158, 500, 14140, 19004, 21928, 44009, 54629, 57148, 260653, 281228, 342280, 519448, 749938, 930866
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OFFSET

1,2


REFERENCES

H. Riesel, "Prime numbers and computer methods for factorization," Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381384.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
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..22.
Ray Ballinger, Proth Search Page
R. M. Robinson, A report on primes of the form k.2^n+1 and on factors of Fermat numbers, Proc. Amer. Math. Soc., 9 (1958), 673681.


MATHEMATICA

Select[Range[2000], PrimeQ[13 4^#+1]&] (* Harvey P. Dale, Jan 22 2011 *)


PROG

(MAGMA) [ n: n in [1..800]IsPrime(13*4^n+1)] // Vincenzo Librandi, Nov 21 2010
(PARI) for(n=1, 10^5, if(ispseudoprime(13*4^n+1), print1(n, ", "))); /* Joerg Arndt, Apr 07 2013 */


CROSSREFS

See A032356 (n such that 13*2^n+1 is prime) for more terms.
Sequence in context: A322468 A116930 A073119 * A101528 A119040 A287578
Adjacent sequences: A002254 A002255 A002256 * A002258 A002259 A002260


KEYWORD

nonn,more


AUTHOR

N. J. A. Sloane


EXTENSIONS

Added more terms (from A032356), Joerg Arndt, Apr 07 2013


STATUS

approved



