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 A065990 #6 Aug 02 2025 12:15:03
%S A065990 1,6,102,131,230
%N A065990 Numbers k such that the first k base-5 digits of Pi expressed in decimal forms a prime.
%e A065990 The first 6 quinary digits of Pi (A004604) are 303232 = 9817 in decimal, which is a prime.
%t A065990 Do[ If[ PrimeQ[ FromDigits[ First[ RealDigits[Pi, 5, n]], 5]], Print[n]], {n, 1, 3600} ]
%Y A065990 Cf. A004604.
%K A065990 base,nonn,more
%O A065990 1,2
%A A065990 _Robert G. Wilson v_, Dec 10 2001