This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A244442 a(n) is the smallest prime p such that all the n numbers dip(p), dip(dip(p)), ..., dip(dip(...(dip(p))...)) are primes. The function dip is defined in the comment lines. 1
 2, 2, 2, 834007, 53918617, 53918617 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS dip(m) is the number that is obtained from m by changing each zero digit of m to 1 and each nonzero digit i of m to the i-th prime. For example dip(103)=2.1.5=215 and dip(19)=2.23=223. Since each positive integer starts with a nonzero digit, dip is well defined. LINKS EXAMPLE a(4)=834007 because the four numbers: 1. dip(834007)=19.5.7.1.1.17=19571117, 2. dip(dip(834007)), 3. dip(dip(dip(834007))), 4. dip(dip(dip(dip(834007)))) are all primes and 834007 is the smallest prime with this property. CROSSREFS Cf. A000040. Sequence in context: A207820 A186069 A280842 * A246471 A079243 A289814 Adjacent sequences:  A244439 A244440 A244441 * A244443 A244444 A244445 KEYWORD nonn,base,more,hard AUTHOR Jahangeer Kholdi and Farideh Firoozbakht, Jul 07 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 April 22 06:14 EDT 2019. Contains 322329 sequences. (Running on oeis4.)