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 A217349 #24 Nov 29 2023 10:47:38 %S A217349 1,2,3,4,5,8,9,10,14,15,19,22,39,44,49,63,80,87,102,107,294,305,399, %T A217349 463,595,599,903,944,1324,1727,1755,1932,1935,4485,6165,6665,9438, %U A217349 11169,19859,27503,55392,86235,98217,117855,123640,134204,139660,150437,157634,186475,236129,283248,390142,410178 %N A217349 Numbers k such that 4^k + 7 is prime. %C A217349 The next terms are > 4.1*10^5. - _Elmo R. Oliveira_, Nov 29 2023 %F A217349 a(n) = A057195(n)/2. %e A217349 For k = 14, 4^14 + 7 = 268435463 is prime. %t A217349 Select[Range[0, 5000], PrimeQ[4^# + 7] &] %o A217349 (PARI) is(n)=ispseudoprime(4^n+7) \\ _Charles R Greathouse IV_, Jun 06 2017 %Y A217349 Cf. A057195, A059266, A089437, A104066 (associated primes). %K A217349 nonn %O A217349 1,2 %A A217349 _Vincenzo Librandi_, Oct 01 2012 %E A217349 Extended using A057195 terms by _Michel Marcus_, Aug 28 2015 %E A217349 a(51)-a(54) derived from A057195 by _Elmo R. Oliveira_, Nov 29 2023