
COMMENTS

This sequence is log2 of A077659. It is known that a(11) > 22. Is it possible that 11^2^k + 12^2^k is composite for all k > 0?
The corresponding primes are listed in A122900. Currently a(n) is unknown for n in {11,15,18,20,28,44,46,49,51,52,53,55,57,58,61,62,64,71,73,77,81,83,91,92,94,...}. All n<100 and 0<k<10 are checked. The first occurrence of each exponent k is listed in A122902.  Alexander Adamchuk, Sep 18 2006
