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 A177030 #17 Jul 15 2023 08:34:33 %S A177030 1,7,9,33,127,153,2327,3607,14803,16431 %N A177030 Numbers k such that 11^k + 3^k - 1 is prime. %C A177030 a(9) > 13518. - _Daniel Starodubtsev_, Apr 06 2020 %F A177030 A177027(n) = 11^a(n)+3^a(n)-1. %e A177030 7 is in the sequence, because 11^7 + 3^7 - 1 = 19489357 is prime. %o A177030 (Magma)[n: n in [0..1500]|IsPrime(11^n+3^n-1^n)] %o A177030 (PARI) is(n)=ispseudoprime(11^n+3^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A177030 Cf. A155623, A177027. %K A177030 nonn,more %O A177030 1,2 %A A177030 _Vincenzo Librandi_, Dec 09 2010 %E A177030 a(7)-a(8) from _Daniel Starodubtsev_, Apr 06 2020 %E A177030 a(9)-a(10) from _Michael S. Branicky_, Jul 15 2023