OFFSET
0,1
COMMENTS
Conjecture: a(n) is the number of letters (0's and 1's) in the n-th iterate of the mapping 00->1000, 10->000, starting with 00; see A288729.
LINKS
Clark Kimberling, Table of n, a(n) for n = 0..2000
Index entries for linear recurrences with constant coefficients, signature (0, 2, 2).
FORMULA
a(n) = 2*a(n-2) + 2*a(n-3) for n >= 3, where a(0) = 2, a(2) = 4, a(3) = 7.
G.f.: (-2 - 4*x - 3*x^2)/(-1 + 2*x^2 + 2*x^3).
MATHEMATICA
LinearRecurrence[{0, 2, 2}, {2, 4, 7}, 40]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 17 2017
STATUS
approved