%I #7 Aug 12 2021 13:02:54
%S 19,55,91,119,127,163,199,235,271,307,335,343,379,415,451,487,523,551,
%T 559,595,631,667,719,739,767,775,811,847,883,919,955,983,991,1027,
%U 1063,1099,1135,1171,1199,1207,1243,1279,1315,1351
%N Numbers n such that string 3,1 occurs in the base 6 representation of n but not of n+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,6],{3,1}]>0,1,0],{n,1400}],{1,0}][[All,1]] (* _Harvey P. Dale_, Aug 12 2021 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_