This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A185240 #39 Feb 16 2025 08:33:13
%S A185240 11,13,79,127,503,617,709,857,1499,3823,135623,280979
%N A185240 Numbers k such that (35^k + 1)/36 is prime.
%C A185240 All terms are primes. a(11) > 10^5.
%H A185240 Paul Bourdelais, <a href="https://listserv.nodak.edu/cgi-bin/wa.exe?A2=NMBRTHRY;417ab0d6.0906">A Generalized Repunit Conjecture</a>
%H A185240 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 A185240 H. Dubner and T. Granlund, <a href="http://www.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 A185240 H. Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a>
%H A185240 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Repunit.html">Repunit</a>
%t A185240 Do[ p=Prime[n]; If[ PrimeQ[ (35^p + 1)/36 ], Print[p] ], {n, 1, 9592} ]
%o A185240 (PARI) is(n)=isprime((35^n+1)/36) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y A185240 Cf. A000978 = numbers n such that (2^n + 1)/3 is prime. Cf. A007658, A057171, A057172, A057173, A057175, A001562, A057177, A057178, A057179, A057180, A057181, A057182, A057183, A057184, A057185, A057186, A057187, A057188, A057189, A057190, A057191, A071380, A071381, A071382. Cf. A084741, A084742, A065507, A126659, A126856.
%K A185240 hard,more,nonn
%O A185240 1,1
%A A185240 _Robert Price_, Aug 29 2013
%E A185240 a(11)=135623 found as probable prime and added by _Paul Bourdelais_, Jul 05 2018
%E A185240 a(12) from _Paul Bourdelais_, Sep 13 2021