A072560 Denominators of w(n) where w(1)=w(2)=w(3)=1, w(n)=(w(n-1)*w(n-2)+(w(n-1)+w(n-2))/3) / w(n-3).

3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1, 3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3

Offset: 1

Author

Benoit Cloitre, Aug 06 2002

Keywords

• nonn
• frac

Comments

Sequence contains 1,3 or 9 only and is periodic with period (3,9,3,3,1,3,3,9,3,3,1,3,3,9,3,1,1,1) of length 18.

Examples

			The sequence w() begins: 1, 1, 1, 5/3, 23/9, 17/3, 31/3, 25, 143/3, 353/3, 2039/9, 1685/3, 3251/3, 2689, 15571/3, ...
		

Links

• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).

Crossrefs

Cf. A072561, A072557.

Programs

Mathematica

LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},{3, 9, 3, 3, 1, 3, 3, 9, 3, 3, 1, 3, 3, 9, 3, 1, 1, 1},105] (* Ray Chandler, Aug 25 2015 *)
PadRight[{},120,{3,9,3,3,1,3,3,9,3,3,1,3,3,9,3,1,1,1}] (* Harvey P. Dale, Apr 04 2022 *)