

A057178


Numbers k such that (12^k + 1)/13 is a prime.


16



5, 11, 109, 193, 1483, 11353, 21419, 21911, 24071, 106859, 139739, 495953
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OFFSET

1,1


COMMENTS

(12^1483 + 1)/13, a 1600digit number, has now been certified prime with Primo.  Rick L. Shepherd, May 01 2002


LINKS

Table of n, a(n) for n=1..12.
Paul Bourdelais, A Generalized Repunit Conjecture
J. Brillhart et al., Factorizations of b^n + 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
H. Lifchitz, Mersenne and Fermat primes field
Eric Weisstein's World of Mathematics, Repunit


MATHEMATICA

lst={}; Do[p=(12^n+1)/13; If[PrimeQ[p], AppendTo[lst, n]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 29 2008 *)


CROSSREFS

Different from A056265.
Sequence in context: A062652 A075706 A236509 * A056265 A302144 A041909
Adjacent sequences: A057175 A057176 A057177 * A057179 A057180 A057181


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Sep 15 2000


EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(10) corresponds to a probable prime, discovered by Paul Bourdelais, Feb 08 2010
a(11) corresponds to a probable prime, discovered by Paul Bourdelais, Sep 21 2011
a(12) corresponds to a probable prime, discovered by Paul Bourdelais, Nov 13 2018


STATUS

approved



