OFFSET
1,2
COMMENTS
a(n) = length of A317199(n).
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1000
Bo Tan and Zhi-Ying Wen, Some properties of the Tribonacci sequence, European Journal of Combinatorics, 28 (2007) 1703-1719. See Prop. 2.9.
Index entries for linear recurrences with constant coefficients, signature (2,0,0,-1).
FORMULA
Bo Tan et al. express a(n) in terms of the tribonacci numbers A000073.
MATHEMATICA
CoefficientList[Series[-x(2x^3+2x^2+x-2)/(x^4-2x+1), {x, 0, 40}], x] (* Harvey P. Dale, Aug 31 2020 *)
PROG
(PARI) my(N=40); Vec(x*(2 - x - 2*x^2 - 2*x^3)/((1 - x)*(1 - x - x^2 - x^3)) + O(x^N), -N) \\ Andrew Howroyd, Oct 24 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Aug 05 2018
EXTENSIONS
Zero prepended by Harvey P. Dale, Aug 31 2020
a(36)-a(38) from Stefano Spezia, Oct 24 2023
STATUS
approved