A283767 Numbers k such that U(k) is even, where U = A001950 = upper Wythoff sequence.

1, 4, 7, 8, 10, 11, 13, 14, 17, 20, 21, 23, 24, 26, 27, 30, 33, 36, 37, 39, 40, 43, 46, 49, 50, 52, 53, 56, 59, 62, 63, 65, 66, 68, 69, 72, 75, 76, 78, 79, 81, 82, 85, 88, 91, 92, 94, 95, 98, 101, 104, 105, 107, 108, 111, 114, 117, 118, 120, 121, 123, 124

Offset: 1

Author

Clark Kimberling, Mar 17 2017

Keywords

• nonn
• easy

Comments

Complement of A283768.

Links

• Clark Kimberling, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001950, A001622, A283765, A283768.

Programs

Mathematica

r = GoldenRatio^2; z = 250; t = Table[Floor[n*r], {n, 1, z}]; u = Mod[t, 2];
Flatten[Position[u, 0]]  (* A283767 *)
Flatten[Position[u, 1]]  (* A283768 *)

Formula

a(n+1) - a(n) is in {1,2,3} for every n.