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%I #11 Aug 25 2021 05:10:21
%S 19,37,68,86,117,139,166,184,215,233,265,282,313,331,362,380,411,429,
%T 460,482,509,527,558,576,608,625,656,674,705,723,754,772,803,825,852,
%U 870,901,919,979,999,1017,1048,1066,1097,1115
%N Numbers k such that 2 and 5 occur juxtaposed in the base-7 representation of k but not of k+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{2,5}]>0 || SequenceCount[IntegerDigits[n,7],{5,2}]>0,1,0],{n,1200}],{1,0}] [[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jul 08 2020 *)
%Y Cf. A007093.
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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