The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A090517 Least k such that floor[(10^n)/k] is prime. 3
 2, 9, 12, 13, 28, 19, 7, 27, 12, 13, 17, 74, 17, 14, 82, 66, 36, 44, 9, 36, 21, 13, 9, 90, 7, 19, 149, 51, 321, 35, 12, 14, 140, 13, 28, 42, 34, 36, 153, 155, 133, 46, 73, 106, 162, 109, 122, 42, 62, 422, 29, 231, 38, 34, 340, 295, 151, 197, 94, 19, 17, 83, 131, 66, 36 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..65. EXAMPLE a(1) = 2 as 10/2 = 5 is a prime. a(3) = 12 as floor[1000/12] = 83 is prime. MATHEMATICA lkp[n_]:=Module[{k=2, c=10^n}, While[!PrimeQ[Floor[c/k]], k++]; k]; Array[ lkp, 70] (* Harvey P. Dale, Jul 09 2018 *) CROSSREFS Cf. A090518, A090519, A090520. Sequence in context: A083159 A041335 A042147 * A092191 A030376 A080520 Adjacent sequences: A090514 A090515 A090516 * A090518 A090519 A090520 KEYWORD base,nonn AUTHOR Amarnath Murthy, Dec 07 2003 EXTENSIONS Corrected and extended by Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Jan 28 2004 Further terms from David Wasserman, Dec 20 2005 STATUS approved

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

Last modified July 15 21:59 EDT 2024. Contains 374334 sequences. (Running on oeis4.)