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%I #7 Feb 17 2024 19:20:37
%S 77,177,277,377,477,577,677,770,877,977,1077,1177,1277,1377,1477,1577,
%T 1677,1770,1877,1977,2077,2177,2277,2377,2477,2577,2677,2770,2877,
%U 2977,3077,3177,3277,3377,3477,3577,3677,3770,3877
%N Numbers n such that string 7,7 occurs in the base 10 representation of n but not of n-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{7,7}]>0,1,0],{n,4000}],{0,1}][[;;,2]] (* _Harvey P. Dale_, Feb 17 2024 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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