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 A089437 #31 Nov 16 2023 07:44:16 %S A089437 1,2,3,6,8,9,14,15,42,114,195,392,555,852,1004,1185,2001,2030,2031, %T A089437 2276,8610,8967,10362,11366,15927,16514,17877,19122,19898,27728,29156, %U A089437 61275,102981,117663,181560,239922,342789,371226,717200,937776,970406,1102722 %N A089437 Numbers k such that 4^k + 3 is prime. %C A089437 The halved even terms of A057732. - _R. J. Mathar_, Feb 26 2008 %e A089437 4^15 + 3 = 1073741827 a prime number. %o A089437 (PARI) is(n)=ispseudoprime(4^n+3) \\ _Charles R Greathouse IV_, Feb 20 2017 %Y A089437 Cf. A057732, A228026 (the actual primes). %K A089437 nonn,more %O A089437 1,2 %A A089437 Herman H. Rosenfeld (herm3(AT)pacbell.net), Dec 28 2003 %E A089437 More terms from _Ray Chandler_, Dec 30 2003 %E A089437 More terms from _R. J. Mathar_, Feb 26 2008 %E A089437 a(33)-a(37) derived from A057732 by _Robert Price_, Apr 26 2014 %E A089437 a(38)-a(42) derived from A057732 by _Amiram Eldar_, Nov 16 2023