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%I #9 Feb 02 2023 19:29:11
%S 21,46,71,96,105,121,146,171,196,221,230,246,271,296,321,346,355,371,
%T 396,421,446,471,480,496,521,525,571,596,605,621,646,671,696,721,730,
%U 746,771,796,821,846,855,871,896,921,946,971
%N Numbers k such that the string 4,1 occurs in the base 5 representation of k but not of k-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,5],{4,1}]>0,1,0],{n,1000}],{0,1}][[All,2]] (* _Harvey P. Dale_, Feb 02 2023 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_