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 A089319 #17 Mar 07 2025 21:29:56
%S A089319 3,2,3,3,6,2,3,6,3,11,7,2,70,2,22,18,43,3,4,649,15,3,37,2,24,13,4,8,
%T A089319 40,77,19,22,13,24,292,48,4,2,109,792,30,4,18,5,7,90,28,138,132,891,9,
%U A089319 25,145,2,24,9,40,28,219,165,40,41,4,13,261,24,6,30,6,154,82,22,120,2,55
%N A089319 Smallest k > 1 such that k^n followed by digit 1 is a prime.
%H A089319 Michael S. Branicky, <a href="/A089319/b089319.txt">Table of n, a(n) for n = 1..1000</a>
%e A089319 a(4) = 3 as concatenation of 3^4 and 1 = 811 is a prime. 161 is not a prime.
%t A089319 Do[k = 2; While[ !PrimeQ[10*k^n + 1], k++ ]; Print[k], {n, 1, 30}] (* _Ryan Propper_, Jul 08 2005 *)
%o A089319 (PARI) a(n) = my(k=2); while (!isprime(10*k^n+1), k++); k; \\ _Michel Marcus_, Mar 07 2025
%Y A089319 Cf. A089318.
%K A089319 base,nonn
%O A089319 1,1
%A A089319 _Amarnath Murthy_, Nov 03 2003
%E A089319 Corrected and extended by _Ryan Propper_, Jul 08 2005
%E A089319 Further terms from _David Wasserman_, Sep 09 2005