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.
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
KEYWORD
nonn
AUTHOR
Chai Wah Wu, Jun 11 2015
STATUS
approved