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 A069589 #17 Jun 20 2024 18:49:43
%S A069589 3,31,307,3001,30011,300007,3000017,30000001,300000007,3000000019,
%T A069589 30000000001,300000000077,3000000000013,30000000000011,
%U A069589 300000000000089,3000000000000037,30000000000000029,300000000000000011,3000000000000000037,30000000000000000041
%N A069589 Smallest prime in which the n-th significant digit is a 3.
%H A069589 Robert Israel, <a href="/A069589/b069589.txt">Table of n, a(n) for n = 1..996</a>
%p A069589 seq(nextprime(3*10^(j-1)-1), j=1..32);
%t A069589 Join[{3},Table[NextPrime[FromDigits[PadRight[{3},n,0]]],{n,2,20}]] (* _Harvey P. Dale_, Jun 15 2015 *)
%o A069589 (Python)
%o A069589 from sympy import nextprime
%o A069589 def a(n): return nextprime(3*10**(n-1)-1)
%o A069589 print([a(n) for n in range(1, 21)]) # _Michael S. Branicky_, Mar 31 2021
%o A069589 (PARI) a(n) = nextprime(3*10^(n-1)); \\ _Michel Marcus_, Mar 31 2021
%Y A069589 Cf. A069588.
%K A069589 base,nonn
%O A069589 1,1
%A A069589 _Amarnath Murthy_, Mar 25 2002
%E A069589 More terms from _Sascha Kurz_, Mar 28 2002