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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A258802 Least base b >= 2 such that prime(n) is an absolute prime in base b with at least 2 distinct digits or 0 if no such base exists. 2
 0, 0, 3, 3, 5, 4, 5, 5, 4, 4, 6, 7, 7, 7, 7, 4, 8, 8, 9, 6, 9, 9, 11, 7, 7, 9, 11, 11, 13, 10, 13, 10, 12, 11, 13, 17, 14, 11, 12, 9, 16, 9, 6, 13, 15, 10, 6, 11, 19, 12, 19, 13, 11, 16, 7, 17, 19, 19, 12, 7, 16, 19, 7, 10, 13, 19, 22, 7, 19, 19, 18, 18, 21, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) < prime(n)-1. This is true since prime(n) in base b > prime(n) has a single digit, prime(n) in base prime(n) is written as 10 which is not an absolute prime and prime(n) in base prime(n)-1 is written as 11 which does not have 2 distinct digits. For 1 <= n <= 10000, A258778 differs from A258802 for 50 values of n. Conjecture: a(n) = 0 if and only if n=1 or n=2. LINKS Chai Wah Wu, Table of n, a(n) for n = 1..10000 Wikipedia, Permutable prime EXAMPLE See example in A258778. CROSSREFS Cf. A003459, A258706, A258778. Sequence in context: A008316 A335952 A290284 * A072820 A204004 A131950 Adjacent sequences:  A258799 A258800 A258801 * A258803 A258804 A258805 KEYWORD nonn AUTHOR Chai Wah Wu, Jun 11 2015 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 August 17 17:59 EDT 2022. Contains 356189 sequences. (Running on oeis4.)