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Smallest number m such that m! ends in exactly n trailing 0's (or 0 if no such m exists).
2

%I #5 Mar 31 2012 10:26:16

%S 0,5,10,15,20,0,25,30,35,40,45,0,50,55,60,65,70,0,75,80,85,90,95,0,

%T 100,105,110,115,120,0,0,125,130,135,140,145,0,150,155,160,165,170,0,

%U 175,180,185,190,195,0,200,205,210,215,220,0,225,230,235,240,245,0,0,250

%N Smallest number m such that m! ends in exactly n trailing 0's (or 0 if no such m exists).

%C The sequence locates the first occurrence of n in A027868.

%C Entries are zero if n is an element of A000966.

%F a(n) = 5*A181578(n).

%Y Cf. A181578

%K nonn

%O 0,2

%A _Lekraj Beedassy_, Nov 02 2010