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 A204341 #11 Feb 16 2025 08:33:16
%S A204341 4,22,27,58,85,94,202,706,8005,80005,700006,800005,7000000000000006,
%T A204341 80000000000000000005,80000000000000000000005,
%U A204341 70000000000000000000000000006,80000000000000000000000000000000000005,700000000000000000000000000000000000000000000006
%N A204341 Smith numbers with either no internal digits or all internal digits are 0.
%C A204341 All semiprimes of the form 7*10^n + 6 and 8*10^n + 5 are in the sequence.
%H A204341 Vincenzo Librandi, <a href="/A204341/b204341.txt">Table of n, a(n) for n = 1..34</a>
%H A204341 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SmithNumber.html">Smith Number</a>
%t A204341 e = 47; Sort[Join[{27}, 2*Select[Flatten[Union[Table[(2*10^n + 2)/2, {n, 0, e}], Table[(a*10^n + 13 - a)/2, {a, {5, 7, 9}}, {n, e}]]], PrimeQ], 5*Select[Table[(8*10^n + 5)/5, {n, e}], PrimeQ]]]
%Y A204341 Cf. A006753.
%K A204341 base,nonn
%O A204341 1,1
%A A204341 _Arkadiusz Wesolowski_, Jan 14 2012