OFFSET
1,1
COMMENTS
The number of terms of this sequence containing n ternary digits is given by {d(n)}={0,0,0,1,1,1,1,2,2,3,3,5,5,8,8,13,13,21,...} for n=1,2,3,... and thus appears to be essentially the doubling-up of the Fibonacci numbers A103609. For example, 2624 = 10121012(base-3) and 2912 = 10222212(base-3) are the only two terms that have 8 digits when written in base 3, so d(8)=2.
(This conjecture is correct - see A223077. - N. J. A. Sloane, Mar 19 2013)
All terms of sequence A173952, defined by b(1)=32 and, for n>1, b(n)=9*b(n-1)+32, appear to be terms of the above sequence {a(n)}; in fact each term b(n) appears to be the largest term of {a(k)} that has 2n+2 digits when written in base 3.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
John W. Layman, Mar 03 2010
STATUS
approved