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 A215439 #18 Sep 08 2022 08:46:03 %S A215439 1,2,4,10,70,134,146,190,218,292,478,7136,15964,19988,100790,111442, %T A215439 181874,202112 %N A215439 Numbers k such that 2^k + k^2 - 1 is prime. %C A215439 a(17) > 150000. - _Giovanni Resta_, Mar 19 2014 %C A215439 a(19) > 3*10^5. - _Robert Price_, Apr 30 2014 %t A215439 Select[Range[0, 9000], PrimeQ[2^# + #^2 - 1] &] %o A215439 (Magma) [n: n in [0..1000] | IsPrime(2^n+n^2-1)] %o A215439 (PARI) is(n)=ispseudoprime(2^n+n^2-1) \\ _Charles R Greathouse IV_, May 22 2017 %Y A215439 Cf. A215434. %K A215439 nonn %O A215439 1,2 %A A215439 _Vincenzo Librandi_, Sep 03 2012 %E A215439 a(13)-a(16) from _Giovanni Resta_, Mar 19 2014 %E A215439 a(17)-a(18) from _Robert Price_, Apr 30 2014