%I #6 Aug 27 2021 21:23:19

%S 2,1,1,1,4,6,8,13,23,37,58,94,154,249,401,649,1052,1702,2752,4453,

%T 7207,11661,18866,30526,49394,79921,129313,209233,338548,547782,

%U 886328,1434109,2320439,3754549,6074986,9829534,15904522,25734057,41638577,67372633

%N a(n) = a(n-1) + a(n-3) + a(n-4), where a(0) = 2, a(1) = 1, a(2) = 1, a(3) = 1.

%C a(n)/a(n-1) -> (1 + sqrt(5))/2 = golden ratio (A001622), so that a( ) has the growth rate of the Fibonacci numbers (A000045).

%H Clark Kimberling, <a href="/A295685/b295685.txt">Table of n, a(n) for n = 0..2000</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 1, 1)

%F a(n) = a(n-1) + a(n-3) + a(n-4), where a(0) = 2, a(1) = 1, a(2) = 1, a(3) = 1.

%F G.f.: (-2 + x + 2 x^3)/(-1 + x + x^3 + x^4).

%t LinearRecurrence[{1, 0, 1, 1}, {2, 1, 1, 1}, 100]

%Y Cf. A001622, A000045.

%K nonn,easy

%O 0,1

%A _Clark Kimberling_, Nov 29 2017