%I
%S 11,119,211,311,411,511,611,711,811,911,1011,1199,1211,1311,1411,1511,
%T 1611,1711,1811,1911,2011,2119,2211,2311,2411,2511,2611,2711,2811,
%U 2911,3011,3119,3211,3311,3411,3511,3611,3711,3811
%N Numbers n such that string 1,1 occurs in the base 10 representation of n but not of n+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{1,1}]>0,1,0],{n,4000}],{1,0}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 22 2018 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
