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 A050528 #17 Sep 08 2022 08:44:58 %S A050528 19,37,73,577,1153,18433,147457,1179649,77309411329,39582418599937, %T A050528 79164837199873,83010348331692982273,332041393326771929089, %U A050528 1328165573307087716353,21760664753063325144711169,196002643346460554954903773880698489798657 %N A050528 Primes of the form 9*2^n+1. %H A050528 Vincenzo Librandi, <a href="/A050528/b050528.txt">Table of n, a(n) for n = 1..25</a> %H A050528 <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a> %p A050528 A050528:=n->`if`(isprime(9*2^n+1),9*2^n+1,NULL): seq(A050528(n), n=1..200); # _Wesley Ivan Hurt_, Aug 09 2014 %t A050528 Select[9*2^Range[150]+1,PrimeQ] (* _Harvey P. Dale_, Aug 08 2014 *) %o A050528 (Magma) [a: n in [0..150] | IsPrime(a) where a is (9*2^n+1) ]; // _Vincenzo Librandi_, Aug 09 2014 %Y A050528 For more terms see A002256. %K A050528 nonn %O A050528 1,1 %A A050528 _N. J. A. Sloane_, Dec 29 1999