A050008 a(n) = floor(a(n-1)/2) if this is positive and not yet in the sequence, otherwise a(n) = 6*a(n-1).

1, 6, 3, 18, 9, 4, 2, 12, 72, 36, 216, 108, 54, 27, 13, 78, 39, 19, 114, 57, 28, 14, 7, 42, 21, 10, 5, 30, 15, 90, 45, 22, 11, 66, 33, 16, 8, 48, 24, 144, 864, 432, 2592, 1296, 648, 324, 162, 81, 40, 20, 120, 60, 360, 180, 1080, 540, 270, 135

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• easy

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]], 2]], r, 6 #[[-1]]]] &, {0, 1}, 57] (* Ivan Neretin, Jul 31 2016 *)

PARI

first(n)=my(v=vector(n),t); v[1]=1; for(i=2,n, t=v[i-1]\2; if(t<2, v[i]=6*v[i-1]; next); for(j=1,i-1, if(v[j]==t, v[i]=6*v[i-1]; next(2))); v[i]=t); v \\ Charles R Greathouse IV, Jul 31 2016