Sequence is probably infinite.
Table of n, a(n) for n=1..28.
It seems that a(n) is asymptotic to c*exp(d*n) with d around 0.33...
Sequence in context: A070325 A199578 A294920 * A046441 A192335 A067993
Adjacent sequences: A076657 A076658 A076659 * A076661 A076662 A076663
Benoit Cloitre, Oct 24 2002