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A182647
a(n) = the largest n-digit number with exactly 5 divisors, a(n) = 0 if no such number exists.
3
0, 81, 625, 2401, 83521, 923521, 7890481, 88529281, 895745041, 9597924961, 96254442001, 988053892081, 9971252437441, 96840734511361, 999706081460641, 9892436613211441, 99510671548640641, 998005893107997601
OFFSET
1,2
COMMENTS
a(n) = the largest n-digit number of the form p^4 (p = prime), a(n) = 0 if no such number exists.
FORMULA
A000005(a(n)) = 5.
MAPLE
A182647 := proc(n) a := 0 ; for i from 1 do p := ithprime(i)^4 ; if A055642(p) > n then return a ; elif A055642(p) = n then a := p; end if; end do: end proc:
MATHEMATICA
Table[Prime[PrimePi[10^(n/4)]]^4, {n, 2, 50}]
CROSSREFS
Sequence in context: A206064 A359607 A016756 * A256590 A322240 A185856
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Nov 27 2010
EXTENSIONS
Mathematica program by Zak Seidov, Nov 27 2010
STATUS
approved