%I
%S 77,177,277,377,477,577,677,779,877,977,1077,1177,1277,1377,1477,1577,
%T 1677,1779,1877,1977,2077,2177,2277,2377,2477,2577,2677,2779,2877,
%U 2977,3077,3177,3277,3377,3477,3577,3677,3779,3877
%N Numbers n such that string 7,7 occurs in the base 10 representation of n but not of n+1.
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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