# [seqfan] Fibonacci numbers that produce primes when their digits (base k) are reversed

Jonathan Post jvospost3 at gmail.com
Mon Feb 22 22:03:35 CET 2010

```Perhaps the array should be in OEIS for which the 10th row is A173268
Fibonacci numbers that produce primes when their digits are reversed.

The 3rd row begins, by inspection of A004686   Fibonacci numbers
written in base 3:
2, 12, 111, 2001, 22122, 1100120
because 12 (base 3) = 5 (base 10) which is fibonacci (and prime), and
R(12) = 21 and 21(base 3) = 7 (base 10) is prime.
Note that 2 and 111 are palindromatic prime (base 3) while other
values yield a different prime than fibonacci when reversed.
"210" is the first value for which the OEIS connvention of deleting
2001 is here because R(2001) = 1002 and 1002 (base 3) = 29 (base 10)
which is prime.
the next palindrome is 22122 because 22122 (base 3) = 233 (base 10) is prime.
the next invokation of killing left-hand zeroes comes with
R(1100120) = 210011 (base 3) = 571 (base 10) is prime.

Would anyone like to generate that array and submit, say, the main
diagonal as a new seq, xreffing as above, and including the array in a
comment?

```