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 A164523 #12 Sep 15 2019 07:56:06 %S A164523 0,1,2,3,5,6,10,17,33,37,42,54,63,75,93,102,142,205,215,305,323,390, %T A164523 457,469,826,1273,3275,4203,5133,7558,12675,14897,18122,18818,25689, %U A164523 26458,41627,51386,71782,80329,85686,88170,97062 %N A164523 Nonnegative numbers n such that 6*2^n-1 is prime. %C A164523 The associated primes are in A007505. %F A164523 a(n) = A002235(n+1)-1. - _R. J. Mathar_, Aug 17 2009 %e A164523 n=0 is in the sequence because 6*2^0-1=5 is prime. n=1 is in the sequence because 6*2^1-1=11 is prime. %o A164523 (PARI) is(n)=ispseudoprime(6*2^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A164523 Cf. A157341. %K A164523 nonn %O A164523 1,3 %A A164523 _Vincenzo Librandi_, Aug 15 2009 %E A164523 Extended by _R. J. Mathar_, Aug 17 2009 %E A164523 a(28)-a(43) from _Donovan Johnson_, Jul 09 2010