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 A065592 #20 Sep 06 2023 06:57:38
%S A065592 2,97,991,99901,99991,9999901,9999991,999999929,9999999929,
%T A065592 99999999907,999999999937,9999999999971,99999999999923,
%U A065592 999999999999947,9999999999999917,99999999999999919,99999999999999997,9999999999999999919,99999999999999999931
%N A065592 Smallest prime beginning with exactly n 9's.
%H A065592 M. F. Hasler, <a href="/A065592/b065592.txt">Table of n, a(n) for n = 0..200</a>
%t A065592 fp[n_]:=Select[Join[10*n+{1,7},100*n+Range[1,99,2]],PrimeQ,1]; With[{ns=Table[FromDigits[PadRight[{},n,9]],{n,20}]}, Join[{2}, Flatten[fp/@ns]]] (* _Harvey P. Dale_, May 12 2012 *)
%Y A065592 Cf. A037071, A065582, A065584 - A065591.
%K A065592 nonn,base
%O A065592 0,1
%A A065592 _Robert G. Wilson v_, Nov 28 2001
%E A065592 Corrected by _Don Reble_, Jan 17 2007
%E A065592 Offset corrected by _Sean A. Irvine_, Sep 06 2023