%I #7 May 01 2023 13:46:04
%S 18,67,116,126,165,214,263,312,361,410,459,469,508,557,606,655,704,
%T 753,802,812,851,882,949,998,1047,1096,1145,1155,1194,1243,1292,1341,
%U 1390,1439,1488,1498,1537,1586,1635,1684,1733,1782
%N Numbers n such that string 2,4 occurs in the base 7 representation of n but not of n-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{2,4}]>0,1,0],{n,1800}],{0,1}][[;;,2]] (* _Harvey P. Dale_, May 01 2023 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_