A169747 a(1)=1; thereafter, a(2n)=a(n), a(2n+1) = a(2n-1)-a(n) if that number is positive and not already in the sequence, otherwise a(2n+1) = a(2n-1)+a(n).

1, 1, 2, 1, 3, 2, 5, 1, 4, 3, 7, 2, 9, 5, 14, 1, 13, 4, 17, 3, 20, 7, 27, 2, 25, 9, 16, 5, 11, 14, 25, 1, 24, 13, 37, 4, 33, 17, 50, 3, 47, 20, 67, 7, 60, 27, 87, 2, 85, 25, 110, 9, 101, 16, 117, 5, 112, 11, 123, 14, 109, 25, 84, 1, 83, 24, 59, 13, 46, 37, 83, 4, 79, 33, 112, 17, 95

Offset

1,3

Comments

Suggested by A005132, A030067, A109671.

Links

Zak Seidov, Table of n, a(n) for n = 1..1000 [From Zak Seidov, May 04 2010]

Mathematica

a={1, 1}; Do[c=If[EvenQ[n], a[[n/2]], If[(b=a[[n-2]]-a[[(n-1)/2]])>0&&FreeQ[a, b], b, a[[n-2]]+a[[(n-1)/2]]]]; AppendTo[a, c], {n, 3, 1000}]; a [From Zak Seidov, May 04 2010]

Crossrefs

Sequence in context: A352961 A116529 A368071 * A269380 A268674 A250470

Adjacent sequences: A169744 A169745 A169746 * A169748 A169749 A169750

Keyword

nonn

Author

N. J. A. Sloane, May 02 2010

Extensions

More terms from Zak Seidov, May 04 2010

Status

approved