A050088 a(n) = floor(a(n-1)/3) if this is positive and not yet in the sequence, otherwise a(n) = 6*a(n-1).

1, 6, 2, 12, 4, 24, 8, 48, 16, 5, 30, 10, 3, 18, 108, 36, 216, 72, 432, 144, 864, 288, 96, 32, 192, 64, 21, 7, 42, 14, 84, 28, 9, 54, 324, 1944, 648, 3888, 1296, 7776, 2592, 15552, 5184, 1728, 576, 3456, 1152, 384, 128, 768, 256, 85, 510

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, 6 #[[-1]]]] &, {0, 1}, 52] (* Ivan Neretin, Jul 31 2016 *)

PARI

first(n)=my(v=vector(n),t); v[1]=1; for(i=2,n, t=v[i-1]\3; 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