A111431 - OEIS

%I #13 Jul 21 2021 07:12:18

%S 0,0,1,1,1,3,13,233,46368,701408733,37889062373143906,

%T 6161314747715278029583501626149,

%U 818706854228831001753880637535093596811413714795418360007

%N a(n) = Fibonacci(tribonacci(n)).

%H Alois P. Heinz, <a href="/A111431/b111431.txt">Table of n, a(n) for n = 0..16</a>

%F a(n) = A000045(A000073(n)).

%e a(0) = Fibonacci(tribonacci(0)) = A000045(A000073(0)) = A000045(0) = 0.

%e a(1) = Fibonacci(tribonacci(1)) = A000045(A000073(1)) = A000045(0) = 0.

%e a(2) = Fibonacci(tribonacci(2)) = A000045(A000073(2)) = A000045(1) = 1.

%e a(3) = Fibonacci(tribonacci(3)) = A000045(A000073(3)) = A000045(1) = 1.

%e a(4) = Fibonacci(tribonacci(4)) = A000045(A000073(4)) = A000045(2) = 1.

%e a(5) = Fibonacci(tribonacci(5)) = A000045(A000073(5)) = A000045(4) = 3.

%e a(6) = Fibonacci(tribonacci(6)) = A000045(A000073(6)) = A000045(7) = 13.

%e a(7) = Fibonacci(tribonacci(7)) = A000045(A000073(7)) = A000045(13) = 233.

%e a(8) = A000045(A000073(8)) = A000045(24) = 46368.

%e a(9) = A000045(A000073(9)) = A000045(44) = 701408733.

%e a(10) = A000045(A000073(10)) = A000045(81) = 37889062373143906.

%p a:= n-> (<<0|1>, <1|1>>^((<<0|1|0>, <0|0|1>, <1|1|1>>^n)[1, 3]))[1, 2]:

%p seq(a(n), n=0..13);  # _Alois P. Heinz_, Aug 09 2018

%t Fibonacci/@LinearRecurrence[{1,1,1},{0,0,1},15] (* _Harvey P. Dale_, Jan 04 2013 *)

%Y Cf. A000045, A000073, A066178, A007570, A111425.

%K easy,nonn

%O 0,6

%A _Jonathan Vos Post_, Nov 13 2005