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 A376933 #18 Mar 01 2025 16:45:01
%S A376933 2,3,9,219,89,707,7139,17397,127107,185573,170099,8513673,3730629,
%T A376933 9645947,20878187,435128997,413502597,7180622897,28071202809,
%U A376933 4197184407,53159437779,72827487477,408466487673,1622948986427,1009480191957,50924645281527,141362538039039
%N A376933 a(n) = (A376907(n) - 10^(n-1))/3.
%t A376933 a[n_]:=(Module[{k=1}, While[!PrimeQ[m=3k^2+3k+1]||IntegerLength[m]<n, k++]; m]-10^(n-1))/3; Array[a, 15]
%o A376933 (Python)
%o A376933 from itertools import count
%o A376933 from math import isqrt
%o A376933 from sympy import isprime
%o A376933 def A376933(n):
%o A376933 for k in count(isqrt((((a:=10**(n-1))<<2)-1)//12)):
%o A376933 m = 3*k*(k+1)+1
%o A376933 if m >= a and isprime(m):
%o A376933 return (m-a)//3 # _Chai Wah Wu_, Oct 13 2024
%o A376933 (PARI) a(n) = my(m=10^(n-1), p); for(k=(sqrtint(12*m-3)-3)\6, oo, p=3*k*(k+1)+1; if(p>m&&isprime(p), return((p-m)/3))); \\ _Jinyuan Wang_, Mar 01 2025
%Y A376933 Cf. A011557, A376907.
%K A376933 nonn,base
%O A376933 1,1
%A A376933 _Stefano Spezia_, Oct 11 2024
%E A376933 a(21)-a(27) from _Chai Wah Wu_, Oct 13 2024