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Position of n-th 5 in A031007.
1

%I #9 Feb 28 2014 01:21:58

%S 5,17,31,45,59,64,66,68,70,72,73,74,76,87,106,127,148,169,190,197,200,

%T 203,206,209,211,212,215,232,253,274,295,316,337,344,347,350,353,356,

%U 358,359,362,379,400,421,442,463,484,491,494

%N Position of n-th 5 in A031007.

%H Vincenzo Librandi, <a href="/A031013/b031013.txt">Table of n, a(n) for n = 1..2000</a>

%t Flatten[Position[Flatten[Table[Reverse[IntegerDigits[n,7]],{n,0,200}]],5]]-1 (* _Harvey P. Dale_, Feb 25 2014 *)

%K nonn

%O 1,1

%A _Clark Kimberling_