%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_