OFFSET
0,3
COMMENTS
Number of ternary trees of height less than n.
The rightmost digits cycle (0, 1, 2, 9, 0, 1, 2, 9, ...).
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..9
Robin Lamarche-Perrin, An Information-theoretic Framework for the Lossy Compression of Link Streams, arXiv:1807.06874 [cs.DS], 2018.
C. Lenormand, Arbres et permutations, 1.2: Magmas et Arborescences, pp. 55, 57.
FORMULA
a(n) is asymptotic to c^(3^n) where c=1.0847999710783722816939038440390528005339362697...
MATHEMATICA
Nest[Append[#, #[[-1]]^3 + 1] &, {0}, 7] (* Michael De Vlieger, Oct 24 2018 *)
PROG
(Sage)
def a(n): return 0 if (n==0) else a(n-1)^3 + 1
[a(n) for n in (0..9)] # G. C. Greubel, Jul 19 2021
KEYWORD
easy,nonn
AUTHOR
Gerald McGarvey, Dec 08 2007
STATUS
approved