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 A135605 #13 Mar 05 2024 16:32:35
%S A135605 1234567891,2,3,4567,5,67,7,89,9101112131,101,11,11,1213,2,13,3,
%T A135605 14151617,41,151,5,
%U A135605 16171819202122232425262728293031323334353637383940414243,61,17,7,181,81920212223242526272829303,19,920212223242526272829303132333435363738394041424344454647484950515253
%N A135605 Consider the infinite string S = 12345678910111213141516171819202122232425262728293031... Sequence gives the first prime that starts at the k-th digit, skipping zero digits.
%C A135605 a(67)>10^5000. - _Robert G. Wilson v_, Mar 01 2008
%H A135605 Robert G. Wilson v, <a href="/A135605/b135605.txt">Table of n, a(n) for n=1..66</a>
%e A135605 Examples from _N. J. A. Sloane_, Feb 24 2021: (Start)
%e A135605 S = 1234567891011121314151617181920212...
%e A135605 The 10th digit is a 1, and the first prime in S that starts with that digit is 101.
%e A135605 The 11th digit is 0, so we skip it.
%e A135605 The 12th digit is 1, and the first prime in S that starts with that digit is 11.
%e A135605 The 13th digit is another 1, and the first prime in S that starts with that digit is another 11.
%e A135605 The 14th digit is another 1, and the first prime in S that starts with that digit is 1213.
%e A135605 And so on. (End)
%t A135605 a[n_] := Block[{m = 0, d = n, i = 1, l, p}, While[m <= d, l = m; m = 9 i*10^(i - 1) + l; i++ ]; i--; p = Mod[d - l, i]; q = Floor[(d - l)/i] + 10^(i - 1); If[p != 0, IntegerDigits[q][[p]], Mod[q - 1, 10]]]; pp[j_, k_] := FromDigits[ Table[ a@i, {i, j, k}]]; f[n_] := Block[{m = n, p}, If[a@n != 0, (While[p = pp[n, m]; ! PrimeQ@ p, m++ ]; p),]]; Array[f, 29] (* _Robert G. Wilson v_, Mar 01 2008 *)
%Y A135605 Cf. A007376, A033307, A073175, A073175, A103575.
%K A135605 nonn,base
%O A135605 1,1
%A A135605 Marcelo Iglesias (markelo(AT)gmail.com), Feb 26 2008
%E A135605 More terms from _Robert G. Wilson v_, Mar 01 2008