%I #7 Apr 27 2020 15:03:48

%S 1,4,22,23,24,25,26,27,28,148,156,164,172,180,188,196,1030,1037,1044,

%T 1051,1058,1065,1072,1080,1087,1094,1101,1108,1115,1122,1130,1137,

%U 1144,1151,1158,1165,1172,1180,1187,1194,1201,1208

%N (s(n)+4)/7, where s(n)=n-th base 7 palindrome that starts with 3.

%t b7p3Q[n_]:=Module[{idn7=IntegerDigits[n,7]},idn7[[1]]==3&&idn7 == Reverse[ idn7]]; (#+4)/7&/@Select[Range[10000],b7p3Q] (* _Harvey P. Dale_, Apr 27 2020 *)

%K nonn,base

%O 1,2

%A _Clark Kimberling_