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 A065832 #17 Sep 25 2024 14:21:04
%S A065832 2,4,10,24,29,34,43,62,76,351,778,2736,4992,7517,22044,40390,204505
%N A065832 Numbers k such that the first k binary digits found in the base-10 expansion of Pi form a prime (when the decimal point is ignored).
%C A065832 In other words, take the decimal expansion of Pi, drop any digits greater than 1, omit the decimal point and look for prefixes in the resulting string which form base-2 primes.
%C A065832 Numbers k such that A065830(k) is prime.
%e A065832 The first a(3)=10 binary digits of Pi are 1101110001_2 which is prime 881_10.
%t A065832 p = First[ RealDigits[ Pi, 10, 10^5]]; p = p[[ Select[ Range[10^5], p[[ # ]] == 0 || p[[ # ]] == 1 & ]]]; Do[ If[ PrimeQ[ FromDigits[ Take[p, n], 2]], Print[n]], {n, 1, Length[p] } ]
%Y A065832 Cf. A065828 up to A065840, A000796, A011545, A011546, A055143, A005042, A060421, A039954, A048796.
%K A065832 nonn,base,hard,more
%O A065832 1,1
%A A065832 _Patrick De Geest_, Nov 24 2001
%E A065832 More terms from _Robert G. Wilson v_, Nov 30 2001
%E A065832 a(15)-a(16) from _Chai Wah Wu_, Apr 06 2020
%E A065832 a(17) from _Michael S. Branicky_, Sep 25 2024