A020943 a(2n+1) = |a(2n) - a(2n-1)|, a(2n) = a(n) + a(n-1).

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

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• look

Comments

Presumably, the positions n such that a(n)=0 are the terms of A097074. - Ivan Neretin, Jul 06 2015

Links

• Ivan Neretin, Table of n, a(n) for n = 1..5461

Crossrefs

Cf. A020947, A020948, A020949, A020950.

Programs

Mathematica

a = {0, 1, 1}; Do[AppendTo[a, a[[n]] + a[[n - 1]]]; AppendTo[a, Abs[a[[-1]] - a[[-2]]]], {n, 2, 51}]; a (* Ivan Neretin, Jul 06 2015 *)

Extensions

More terms from Henry Bottomley, May 16 2001