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 A215440 #17 Jun 01 2025 13:11:35 %S A215440 1,3,5,9,65,71,225,269,651,843,1971,4851,13667,13961,33309,168111 %N A215440 Numbers k such that 3^k + k^3 - 1 is prime. %C A215440 a(17) > 2*10^5. - _Robert Price_, Apr 15 2014 %t A215440 Select[Range[0, 3000], PrimeQ[3^# + #^3 - 1] &] %o A215440 (Magma) [k: k in [0..800] | IsPrime(3^k + k^3 - 1)]; %o A215440 (PARI) is(n)=ispseudoprime(3^n+n^3-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A215440 Cf. A215435. %K A215440 nonn,more %O A215440 1,2 %A A215440 _Vincenzo Librandi_, Sep 03 2012 %E A215440 a(12)-a(16) from _Robert Price_, Apr 15 2014