A050124 a(1)=1; for n > 1, a(n) = floor(a(n-1)/5) if this is not among 0,a(1),...,a(n-1); otherwise a(n) = 2*a(n-1).

1, 2, 4, 8, 16, 3, 6, 12, 24, 48, 9, 18, 36, 7, 14, 28, 5, 10, 20, 40, 80, 160, 32, 64, 128, 25, 50, 100, 200, 400, 800, 1600, 320, 640, 1280, 256, 51, 102, 204, 408, 81, 162, 324, 648, 129, 258, 516, 103, 206, 41, 82, 164, 328, 65

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

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

Crossrefs

Cf. A050000 and references therein.

Programs

Mathematica

Rest@Nest[Append[#, If[FreeQ[#, r = Quotient[#[[-1]], 5]], r, 2 #[[-1]]]] &, {0, 1}, 53] (* Ivan Neretin, Jul 31 2016 *)