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Numbers k such that 1 and 3 occur juxtaposed in the base-7 representation of k but not of k-1.
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%I #11 Aug 22 2021 20:50:32

%S 10,22,59,70,108,120,154,169,206,218,255,267,304,316,353,365,402,413,

%T 451,463,490,549,561,598,610,647,659,696,708,745,756,794,806,840,855,

%U 892,904,941,953,990,1002,1039,1051,1078,1137

%N Numbers k such that 1 and 3 occur juxtaposed in the base-7 representation of k but not of k-1.

%t Select[Range[1200],MemberQ[Sort/@Partition[IntegerDigits[#,7],2,1], {1,3}] && !MemberQ[Sort/@Partition[IntegerDigits[#-1,7],2,1],{1,3}]&] (* _Harvey P. Dale_, Aug 10 2011 *)

%Y Cf. A007093.

%K nonn,base

%O 1,1

%A _Clark Kimberling_