%I
%S 3,5,7,17,31,53,97,173,313,557,997,1777,3137,5623,9973,17761,31607,
%T 56209,99991,177823,316223,562337,999983,1778279,3162277,5623403,
%U 9999991,17782769,31622743,56234069,99999989,177827917,316227731,562341293,999999937,1778279401,3162277633,5623413241,9999999967,17782794047,31622776589,56234132519,99999999977,177827941003,316227766003,562341325181,999999999989,1778279410013,3162277660153
%N Fourth root of largest ndigit number with exactly five divisors
%e a(2) = 3 since 3^4 = 81, the largest 2digit number with exactly five divisors (1, 3, 9, 27, 81). All higher 2digit numbers (82 to 99) have either fewer or more divisors than 81.
%t Table[Prime[PrimePi[10^(n/4)]],{n,2,50}]
%Y a(n)=(A182647(n))^(1/4).
%K nonn,base
%O 2,1
%A _Zak Seidov_, Nov 27 2010
