%I #14 Jul 23 2023 01:49:53
%S 1,5,21,22,23,24,25,101,107,113,119,125,501,506,511,516,521,527,532,
%T 537,542,547,553,558,563,568,573,579,584,589,594,599,605,610,615,620,
%U 625,2501,2531,2561,2591,2621,2627,2657,2687,2717
%N a(n) = (s(n) + 1)/5, where s(n) = n-th base-5 palindrome that starts with 4.
%H Harvey P. Dale, <a href="/A043053/b043053.txt">Table of n, a(n) for n = 1..937</a> (all terms up to 5 million)
%t b5s4Q[n_]:=Module[{idn5=IntegerDigits[n,5]},idn5[[1]]==4&&idn5 == Reverse[ idn5]]; (#+1)/5&/@Select[Range[30000],b5s4Q] (* _Harvey P. Dale_, Jun 22 2022 *)
%K nonn,base
%O 1,2
%A _Clark Kimberling_