The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A076449 Least number whose digits can be used to form exactly n different primes (not necessarily using all digits). 6
 1, 2, 25, 13, 37, 107, 127, 113, 167, 1027, 179, 137, 1036, 1127, 1013, 1137, 1235, 1136, 1123, 1037, 1139, 1079, 10124, 10126, 1349, 1279, 1237, 3479, 10699, 1367, 10179, 1379, 10127, 10079, 10138, 10123, 10234, 10235, 10247, 10339, 10267 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Smallest m such that A039993(m) = n. - M. F. Hasler, Mar 08 2014 Mike Keith conjectures that a(n) always exists and reports that he has checked this for n <= 66. - N. J. A. Sloane, Jan 25 2008 LINKS Robert G. Wilson v, Table of n, a(n) for n = 0..457 C. K. Caldwell, The Prime Glossary, Primeval Number J. P. Delahaye, Primes Hunters, 1379 is very primeval (in French) [broken link] Mike Keith, Integers containing many embedded primes W. Schneider, PrimevalNumbers G. Villemin's Almanach of Numbers, Nombre Primeval de Mike Keith FORMULA a(n) = min { m | A039993(m)=n } = min A039993^{-1}(n). - M. F. Hasler, Mar 08 2014 EXAMPLE a(10) = 179 because 179 is the least number harboring ten primes (namely 7, 17, 19, 71, 79, 97, 179, 197, 719, 971). MATHEMATICA (* first do *) Needs["DiscreteMath`Combinatorica`"] (* then *) f[n_] := Length[ Select[ FromDigits /@ Flatten[ Permutations /@ Subsets[ IntegerDigits[ n]], 1], PrimeQ[ # ] &]]; t = Table[0, {50}]; Do[ a = f[n]; If[a < 50 && t[[a + 1]] == 0, t[[a + 1]] = n], {n, 12500}]; t (* Robert G. Wilson v, Feb 12 2005 *) PROG (PARI) A076449(n)=for(m=1, 9e9, A039993(m)==n&&return(n)) \\ Not very efficient. - M. F. Hasler, Mar 08 2014 CROSSREFS Cf. A075053, A072857 gives a similar sequence. Sequence in context: A249634 A161575 A036502 * A153811 A101962 A092045 Adjacent sequences:  A076446 A076447 A076448 * A076450 A076451 A076452 KEYWORD base,nonn AUTHOR Lekraj Beedassy, Nov 07 2002 EXTENSIONS Edited by Robert G. Wilson v, Nov 24 2002 Keith link repaired by Charles R Greathouse IV, Aug 13 2009 Definition reworded by M. F. Hasler, Mar 08 2014 a(26) corrected by Robert G. Wilson v, Mar 12 2014 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 February 17 21:35 EST 2020. Contains 332006 sequences. (Running on oeis4.)