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 A088603 #10 Sep 23 2023 03:15:47 %S A088603 2,23,233,2333,23333,233993,2339933,23399339,1979339333,23339531339, %T A088603 293999994791,3733799959397,233323747999733,2333939994739931, %U A088603 23833939369399333,238339393693993337,23833939369399333613 %N A088603 a(n) = smallest prime in which n substrings containing the most significant digit are primes. %C A088603 Agrees with A127889 for 8 terms, but A127889 ends there while this sequence continues. - _Ray Chandler_, Mar 13 2007 %o A088603 (PARI) f(n, d, spare) = local(p, r); if (!d, return(n)); for (i = 0, 9, p = 10*n + i; if (isprime(p) || spare, r = f(p, d - 1, spare - 1 + isprime(p))); if (r, return(r))); 0; %o A088603 a(n) = local(i, r); i = 0; while (1, r = f(0, n + i, i); if (r, return(r), i++)); \\ _David Wasserman_, Aug 12 2005 %Y A088603 Cf. A088604, A127889. %K A088603 base,nonn %O A088603 1,1 %A A088603 _Amarnath Murthy_, Oct 15 2003 %E A088603 Corrected and extended by _David Wasserman_, Aug 12 2005