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%I #13 Nov 21 2013 12:47:03
%S 84,184,284,384,484,584,684,784,840,884,984,1084,1184,1284,1384,1484,
%T 1584,1684,1784,1840,1884,1984,2084,2184,2284,2384,2484,2584,2684,
%U 2784,2840,2884,2984,3084,3184,3284,3384,3484,3584
%N Numbers n such that string '84' occurs in the base 10 representation of n but not of n-1.
%t Select[Range[4000],MemberQ[Partition[IntegerDigits[#],2,1], {8,4}]&&!MemberQ[Partition[IntegerDigits[#-1],2,1],{8,4}]&] (* _Harvey P. Dale_, Mar 14 2011 *)
%t Select[Range[4000],!StringFreeQ[ToString[#],"84"]&&StringFreeQ[ToString[#-1],"84"]&]
%t (* Zak Seidov Mar 14 2011 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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