

A174336


a(n) = the smallest ndigit number with exactly 5 divisors, or 0 if no such number exists.


2



0, 16, 625, 2401, 14641, 130321, 1874161, 12117361, 104060401, 1026625681, 10098039121, 100469346961, 1036488922561, 10106606869921, 100091400875761, 1011133218419041, 10028029413722401, 100004631514837921, 1000534329357902641, 10002039828958828561
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OFFSET

1,2


COMMENTS

a(n) = the smallest ndigit number of the form p^4 (p = prime), a(n) = 0 if no such number exists.


LINKS

Robert Israel, Table of n, a(n) for n = 1..999


FORMULA

A000005(a(n)) = 5.


MAPLE

0, seq(nextprime(floor(10^((n1)/4)))^4, n=2..30); # Robert Israel, Dec 05 2016


MATHEMATICA

Table[p=Ceiling[10^((n1)/4)]; While[p^4<10^n && ! PrimeQ[p], p=NextPrime[p]]; If[p^4<10^n, p^4, 0], {n, 20}]


PROG

(MAGMA) [0] cat [NextPrime(Floor(10^((n1)/4)))^4: n in [2..25]]; // Vincenzo Librandi, Dec 06 2016


CROSSREFS

See A182647(n)  the largest ndigit number with exactly 5 divisors.
Sequence in context: A307943 A171210 A266129 * A135786 A016792 A077204
Adjacent sequences: A174333 A174334 A174335 * A174337 A174338 A174339


KEYWORD

nonn,base


AUTHOR

Jaroslav Krizek, Nov 27 2010


EXTENSIONS

Extended by T. D. Noe, Nov 29 2010


STATUS

approved



