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Numbers n such that string 4,5 occurs in the base 10 representation of n but not of n-1.
1

%I #10 Aug 15 2014 02:41:40

%S 45,145,245,345,445,450,545,645,745,845,945,1045,1145,1245,1345,1445,

%T 1450,1545,1645,1745,1845,1945,2045,2145,2245,2345,2445,2450,2545,

%U 2645,2745,2845,2945,3045,3145,3245,3345,3445,3450

%N Numbers n such that string 4,5 occurs in the base 10 representation of n but not of n-1.

%H Vincenzo Librandi, <a href="/A044377/b044377.txt">Table of n, a(n) for n = 1..1250</a>

%t Flatten[Position[Partition[If[MemberQ[Partition[IntegerDigits[#],2,1],{4,5}],1,0]&/@Range[3500],2,1],{0,1}]]+1 (* _Harvey P. Dale_, Aug 14 2014 *)

%K nonn,base

%O 1,1

%A _Clark Kimberling_