This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A174336 a(n) = the smallest n-digit 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = the smallest n-digit 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^((n-1)/4)))^4, n=2..30); # Robert Israel, Dec 05 2016 MATHEMATICA Table[p=Ceiling[10^((n-1)/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^((n-1)/4)))^4: n in [2..25]]; // Vincenzo Librandi, Dec 06 2016 CROSSREFS See A182647(n) - the largest n-digit 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 10 15:09 EST 2019. Contains 329896 sequences. (Running on oeis4.)