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 A133856 #21 Sep 24 2024 06:19:41 %S A133856 0,4,14,8,11,22420,78,17,24,20,25,24,63,30,42,69,128,50,119,204,2816, %T A133856 76,52,288,64,66,184,153,67,268,78,210,438,295,96,74,136,128,2900, %U A133856 1898,130,92,381,106,18626,97,98,1650,747,109,214,113,312,354,1702,560,2798,123,171,554,11210,834,208,990,9271 %N A133856 Least number k > (2n-1) such that (2n-1)^k - 2 is prime, or 0 if no such number exists. %C A133856 a(66) > 40000. - _Robert Price_, Mar 02 2015 %H A133856 Henri Lifchitz & Renaud Lifchitz: <a href="http://www.primenumbers.net/prptop/prptop.php">PRP Records. Probable Primes Top 10000</a>. %F A133856 A128472(n) = (2n-1)^a(n) - 2 for n > 1. %Y A133856 Cf. A128472 (smallest prime of the form (2n-1)^k - 2 for k > (2n-1), or 0 if no such number exists). %Y A133856 Cf. A084714 (smallest prime of the form (2n-1)^k - 2, or 0 if no such number exists). %Y A133856 Cf. A014224, A109080, A090669, A128455, A128457, A128458, A128459, A128460, A128461. %Y A133856 Cf. A133858, A133982. %K A133856 nonn %O A133856 1,2 %A A133856 _Alexander Adamchuk_, Oct 01 2007 %E A133856 a(6) = 22420 was found by _Rick L. Shepherd_, Sep 29 2009 %E A133856 a(21)-a(44) from _Max Alekseyev_, Oct 04 2007 %E A133856 a(45)-a(65) from _Robert Price_, Mar 02 2015