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 A083976 #13 Mar 25 2019 14:02:05
%S A083976 5,15451,15551,1550551,154555451,155535551,355555553,35555155553,
%T A083976 75555555557,1555550555551,152555555555251,10555555355555501,
%U A083976 15505555555550551,35555555755555553,1555555055505555551,1555555551555555551,115555555555555555511
%N A083976 Smallest palindromic prime containing exactly n 5's.
%H A083976 Chai Wah Wu, <a href="/A083976/b083976.txt">Table of n, a(n) for n = 1..500</a>
%t A083976 Table[d = 5; i = 1;
%t A083976 While[ x = IntegerDigits[Prime[i]];
%t A083976 x != Reverse[x] || Count[x, d] != n , i++];
%t A083976 FromDigits[x], {n, 1, 6}] (* _Robert Price_, Mar 25 2019 *)
%Y A083976 Cf. A083972, A083973, A083974, A083976, A083977, A083978, A083979, A083980, A083981.
%K A083976 base,nonn
%O A083976 1,1
%A A083976 _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 21 2003
%E A083976 More terms from _Giovanni Resta_, Feb 08 2006