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 A120491 #23 Oct 24 2024 14:33:51 %S A120491 0,1,2,4,5,10,12,14,24,34,37,52,56,65,68,96,106,128,156,169,236,254, %T A120491 481,618,641,672,700,774,1274,1625,1841,4650,6030,8372,8760,9173, %U A120491 12776,13873,25214,25548,33834,72005 %N A120491 Numbers k such that 22*3^k + 1 is prime. %e A120491 If k=96 then 22*3^k + 1 is a prime with 48 digits. %t A120491 Select[Range[0, 2000], PrimeQ[22*3^# + 1] &] (* _Stefan Steinerberger_, Aug 06 2006 *) %o A120491 (Magma) [ n: n in [0..3000] | IsPrime(22*3^n + 1) ]; // _Vincenzo Librandi_, Jan 31 2011 %o A120491 (PARI) is(n)=ispseudoprime(22*3^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A120491 Cf. A003306. %K A120491 nonn,more %O A120491 1,3 %A A120491 _Parthasarathy Nambi_, Aug 04 2006 %E A120491 More terms from _Stefan Steinerberger_, Aug 06 2006 %E A120491 a(32)-a(41) from _Michael S. Branicky_, Jul 14 2023 %E A120491 a(42) from _Michael S. Branicky_, Oct 24 2024