A110044 a(0) = 11, a(1) = 23; for n > 1, a(n) = |a(n-1) - a(n-2)|.

11, 23, 12, 11, 1, 10, 9, 1, 8, 7, 1, 6, 5, 1, 4, 3, 1, 2, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1

Offset: 0

Author

Edwin F. Sampang, Jul 09 2005

Keywords

• nonn
• easy

Comments

Since a(18)=a(19)=1, starting from here the sequence is periodic with period 3: 1,1,0,1,1,0,1,1,0,... - Emeric Deutsch, Jul 13 2005

Links

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

Crossrefs

Cf. A141571.

Programs

Maple

a[0]:=11: a[1]:=23: for n from 2 to 120 do a[n]:=abs(a[n-1]-a[n-2]) od: seq(a[n],n=0..120); # Emeric Deutsch, Jul 13 2005

Mathematica

Join[{11, 23, 12, 11, 1, 10, 9, 1, 8, 7, 1, 6, 5, 1, 4, 3, 1, 2},LinearRecurrence[{0, 0, 1},{1, 1, 0},85]] (* Ray Chandler, Aug 25 2015 *)

Formula

a(n) = 2/3 + 1/3*cos(2*Pi*n/3) + 1/3*3^(1/2)*sin(2*Pi*n/3) for n >= 19. - Richard Choulet, Dec 12 2008

Extensions

More terms from Emeric Deutsch, Jul 13 2005