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%I #11 Mar 07 2024 11:27:38
%S 67,76,167,176,267,276,367,376,467,476,567,576,667,679,769,776,867,
%T 876,967,976,1067,1076,1167,1176,1267,1276,1367,1376,1467,1476,1567,
%U 1576,1667,1679,1769,1776,1867,1876,1967,1976,2067
%N Numbers k such that 6 and 7 occur juxtaposed in the base-10 representation of k but not of k+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{6,7}]>0 || SequenceCount[ IntegerDigits[ n],{7,6}]>0,1,0],{n,2100}],{1,0}][[;;,1]] (* _Harvey P. Dale_, Mar 07 2024 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_