A050170 a(1) = 1, a(n) = floor(a(n-1)/sqrt(5)) if this is not among 0,a(1),...,a(n-1); otherwise a(n) = floor(a(n-1)*sqrt(5)).

1, 2, 4, 8, 3, 6, 13, 5, 11, 24, 10, 22, 9, 20, 44, 19, 42, 18, 40, 17, 7, 15, 33, 14, 31, 69, 30, 67, 29, 12, 26, 58, 25, 55, 122, 54, 120, 53, 23, 51, 114, 50, 111, 49, 21, 46, 102, 45, 100, 223, 99, 221, 98, 43, 96, 214, 95, 212, 94, 210

Offset

1,2

Comments

Does every positive integer occur exactly once?

Records occur at indices 1, 2, 3, 4, 7, 10, 15, 26, 35, 50, 87, 124, 179, 306, ... with corresponding values 1, 2, 4, 8, 13, 24, 44, 69, 122, 223, 348, 614, 1118, 1744, .... - Peter Kagey, Jan 24 2018

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Mathematica

a[1] = 1; a[n_] := a[n] = If[FreeQ[Join[{0}, Array[a, n-1]], f = Floor[a[n-1]/Sqrt[5]]], f, Floor[a[n-1]*Sqrt[5]]]; Array[a, 60] (* Jean-François Alcover, Sep 12 2017 *)

Crossrefs

Sequence in context: A340730 A101942 A344534 * A087089 A367750 A197382

Adjacent sequences: A050167 A050168 A050169 * A050171 A050172 A050173

Keyword

nonn,look

Author

Clark Kimberling

Status

approved