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%I #25 Aug 20 2021 10:01:57
%S 17,37,157,163,631,7351,26183,30713,41201,77951,476929
%N Numbers n such that (19^n + 1)/20 is a prime.
%H P. Bourdelais, <a href="https://listserv.nodak.edu/cgi-bin/wa.exe?A2=NMBRTHRY;417ab0d6.0906">A Generalized Repunit Conjecture</a>
%H J. Brillhart et al., <a href="http://dx.doi.org/10.1090/conm/022">Factorizations of b^n +- 1</a>, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
%H H. Dubner and T. Granlund, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL3/DUBNER/dubner.html">Primes of the Form (b^n+1)/(b+1)</a>, J. Integer Sequences, 3 (2000), #P00.2.7.
%H H. Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a>
%t Select[Range[0, 10000], PrimeQ[((19^# + 1) / 20)] &] (* _Vincenzo Librandi_, Mar 20 2015 *)
%o (PRIME95) PRP=1,19,476929,1,0,0,"20" # _Paul Bourdelais_, Mar 20 2015
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Sep 15 2000
%E 26183 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
%E a(8)-a(9) give probable primes discovered by _Paul Bourdelais_, Mar 15 2010
%E a(10) gives a probable prime discovered by _Paul Bourdelais_, Mar 18 2010
%E a(11) gives a probable prime discovered by _Paul Bourdelais_, Mar 20 2015
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