

A128460


Numbers n such that 19^n  2 is a prime.


13



1, 2, 3, 13, 14, 19, 20, 23, 38, 1124, 7592, 11755, 12155, 12915, 14172, 15500, 20255, 28388, 184650
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OFFSET

1,2


COMMENTS

No more terms through 50000.  Ryan Propper, Dec 04 2008
a(20) > 2*10^5.  Robert Price, Oct 22 2014


LINKS

Table of n, a(n) for n=1..19.


MATHEMATICA

Do[ f = 19^n  2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 1000} ]


PROG

(MAGMA) [n: n in [0..1000]  IsPrime(19^n2)]; // Vincenzo Librandi, Oct 23 2014


CROSSREFS

Cf. A084714 = smallest prime of the form (2n1)^k  2, or 0 if no such number exists. Cf. A128472 = smallest prime of the form (2n1)^k  2 for k>(2n1), or 0 if no such number exists. Cf. A014224, A109080, A090669, A128455, A128457, A128458, A128459, A128461.
Sequence in context: A171483 A100385 A250184 * A273617 A101541 A299543
Adjacent sequences: A128457 A128458 A128459 * A128461 A128462 A128463


KEYWORD

hard,more,nonn


AUTHOR

Alexander Adamchuk, Mar 14 2007


EXTENSIONS

1124 from Stefan Steinerberger, May 05 2007
7592 from Ryan Propper, Dec 31 2007
Additional terms from Ryan Propper, Dec 04 2008
a(19) from Robert Price, Oct 22 2014


STATUS

approved



