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 A065987 #27 Dec 19 2024 23:39:20
%S A065987 2,23,31,35,124,323,2787,5717,6506,8980,106817,109773,125244,242974,
%T A065987 246353
%N A065987 Numbers k such that the first k binary digits of Pi expressed in decimal forms a prime.
%e A065987 The first 23 binary digits of Pi (A004601) are 11001001000011111101101 = 6588397 in decimal, which is a prime.
%t A065987 Do[ If[ PrimeQ[ FromDigits[ First[ RealDigits[Pi, 2, n]], 2]], Print[n]], {n, 1, 7000} ]
%Y A065987 Cf. A004601, A117721 (the primes themselves), A333649.
%K A065987 base,nonn,more
%O A065987 1,1
%A A065987 _Robert G. Wilson v_, Dec 10 2001
%E A065987 a(10) from _Hans Havermann_, Jul 23 2006
%E A065987 a(11) from _Hans Havermann_, Sep 06 2006
%E A065987 a(12)-a(13) from _Michael S. Branicky_, Sep 17 2024
%E A065987 a(14)-a(15) from _Michael S. Branicky_, Dec 19 2024