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%I #7 Jul 08 2019 14:47:00
%S 90,190,290,390,490,590,690,790,890,909,990,1090,1190,1290,1390,1490,
%T 1590,1690,1790,1890,1909,1990,2090,2190,2290,2390,2490,2590,2690,
%U 2790,2890,2909,2990,3090,3190,3290,3390,3490,3590
%N Numbers n such that string 9,0 occurs in the base 10 representation of n but not of n+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{9,0}]>0,1,0],{n,3600}],{1,0}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jul 08 2019 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_