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 A259298 #30 Jul 23 2024 08:50:31 %S A259298 0,1,2,11,22,40,79,145,152,244,271,1471,2516,3460,4130,4550,7534, %T A259298 12973,14051,14176,16093,16952,28565,121319 %N A259298 Numbers k such that k^2*2^k + 3 is prime. %C A259298 Primes: 3, 5, 19, 247811, 2030043139, 1759218604441603,... %e A259298 2 is in this sequence because 2^2*2^2 + 3 = 19 and 19 is prime. %t A259298 Select[Range[0, 10000], PrimeQ[#^2 2^# + 3] &] (* _Vincenzo Librandi_, Jun 25 2015 *) %o A259298 (Magma) [n: n in [0..1000] | IsPrime(n^2*2^n+3)]; %o A259298 (PARI) is(n)=ispseudoprime(n^2*2^n+3) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A259298 Cf. A058780. %K A259298 nonn,more %O A259298 1,3 %A A259298 _Juri-Stepan Gerasimov_, Jun 23 2015 %E A259298 More terms from _Vincenzo Librandi_, Jun 25 2015 %E A259298 a(18)-a(22) from _Jinyuan Wang_, May 15 2020 %E A259298 a(23) from _Michael S. Branicky_, Apr 20 2023 %E A259298 a(24) from _Michael S. Branicky_, Jul 23 2024