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

Author

N. J. A. Sloane, May 02 2010

Keywords

• nonn

Comments

Suggested by A005132, A030067, A109671.

Links

• Zak Seidov, Table of n, a(n) for n = 1..1000. - _Zak Seidov_, May 04 2010

Programs

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 (* Zak Seidov, May 04 2010 *)

Extensions

More terms from Zak Seidov, May 04 2010