%I
%S 14,63,98,112,161,210,259,308,357,406,441,455,504,553,602,651,686,749,
%T 784,798,847,896,945,994,1043,1092,1127,1141,1190,1239,1288,1337,1386,
%U 1435,1470,1484,1533,1582,1631,1680,1729,1778
%N Numbers n such that string 2,0 occurs in the base 7 representation of n but not of n1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{2,0}]>0,1,0],{n,1800}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 23 2020 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
