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%I #24 Oct 17 2017 13:01:49
%S 3,7,401,449,109037
%N Numbers n such that (38^n - 1)/37 is prime.
%C No other terms < 100000. - _Robert Price_, Dec 23 2011
%H H. Dubner, <a href="http://dx.doi.org/10.1090/S0025-5718-1993-1185243-9">Generalized repunit primes</a>, Math. Comp., 61 (1993), 927-930.
%H H. Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a>
%H <a href="/index/Pri#primepop">Index to primes in various ranges</a>, form ((k+1)^n-1)/k
%t Select[Prime[Range[100]],PrimeQ[(38^#-1)/37]&]
%o (PARI) is(n)=ispseudoprime((38^n-1)/37) \\ _Charles R Greathouse IV_, Feb 17 2017
%K hard,more,nonn
%O 1,1
%A _Alexander Adamchuk_, Feb 11 2007
%E a(5) corresponds to a probable prime discovered by _Paul Bourdelais_, Oct 17 2017
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