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 A188574 #12 Jun 13 2017 13:46:56 %S A188574 1,3,5,7,13,15,35,43,159,245,265,1573,1827,3359,3949,4615,5463,5919, %T A188574 19723 %N A188574 Numbers n such that n^2 + 2*n + 2^n is prime. %t A188574 Select[Range[1, 10000, 2], PrimeQ[#^2 + 2 # + 2^#] &] %o A188574 (PARI) is(n)=ispseudoprime(n^2+2*n+2^n) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A188574 Cf. A220425 (see the comment by _Jonathan Vos Post_). %K A188574 nonn %O A188574 1,2 %A A188574 _Vincenzo Librandi_, Jan 07 2013 %E A188574 a(19) from _Bruno Berselli_, Jan 09 2013