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 A049386 #28 Aug 07 2021 18:37:45 %S A049386 1,2,3,5,6,8,9,10,11,12,13,15,16,17,18,19,20,21,22,23,24,26,27,28,29, %T A049386 30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,49,50,51,52,53, %U A049386 54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72 %N A049386 Binary order of 2^n-th prime. %H A049386 Jinyuan Wang, <a href="/A049386/b049386.txt">Table of n, a(n) for n = 0..78</a> %F A049386 a(n) = A029837(A033844(n)). %F A049386 a(n) = ceiling(log_2(prime(2^n))). %e A049386 The 549755813888th = (2^39)th prime is 16149760533341, whose binary order is 44: it is ceiling(43.87657801)=44, so a(39)=44; %e A049386 a(0)=1 is the binary order of the (2^0)th = 1st prime (= 2), which is log_2(2) = 1. %o A049386 (PARI) a(n) = ceil(log(prime(2^n))/log(2)); \\ _Michel Marcus_, Aug 07 2021 %Y A049386 Cf. A006988, A029837, A033844. %K A049386 nonn %O A049386 0,2 %A A049386 _Labos Elemer_ %E A049386 a(40)-a(57) from _Michel Marcus_, Aug 25 2019 %E A049386 More terms from _Jinyuan Wang_, Aug 07 2021