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 A083973 #19 Mar 25 2019 12:50:25
%S A083973 2,12421,72227,1221221,3222223,122232221,322222223,12222122221,
%T A083973 1202222222021,1222227222221,9222222222229,122222232222221,
%U A083973 32222322222322223,72222222422222227,1202222222222222021,1222222226222222221,125222222222222222521,722222222202222222227
%N A083973 Smallest palindromic prime containing exactly n 2's.
%H A083973 Chai Wah Wu, <a href="/A083973/b083973.txt">Table of n, a(n) for n = 1..500</a>
%t A083973 Table[d = 2; i = 1;
%t A083973 While[ x = IntegerDigits[Prime[i]];
%t A083973 x != Reverse[x] || Count[x, d] != n , i++];
%t A083973 FromDigits[x], {n, 1, 6}] (* _Robert Price_, Mar 25 2019 *)
%Y A083973 Cf. A083972, A083974, A083975, A083976, A083977, A083978, A083979, A083980, A083981.
%K A083973 base,nonn
%O A083973 1,1
%A A083973 _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 21 2003
%E A083973 Corrected and extended by _Giovanni Resta_, Feb 08 2006