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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
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
EXAMPLE
See example in A258778.
CROSSREFS
KEYWORD
nonn
AUTHOR
Chai Wah Wu, Jun 11 2015
STATUS
approved