A050080 a(n) = floor(a(n-1)/3) if this is not among 0, a(1), ..., a(n-2); otherwise a(n) = 4*a(n-1).

1, 4, 16, 5, 20, 6, 2, 8, 32, 10, 3, 12, 48, 192, 64, 21, 7, 28, 9, 36, 144, 576, 2304, 768, 256, 85, 340, 113, 37, 148, 49, 196, 65, 260, 86, 344, 114, 38, 152, 50, 200, 66, 22, 88, 29, 116, 464, 154, 51, 17, 68, 272, 90, 30, 120, 40, 13

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]], 3]], r, 4 #[[-1]]]] &, {0, 1}, 56] (* Ivan Neretin, Jul 31 2016 *)