A050088 - OEIS

%I #12 Oct 05 2019 11:31:44

%S 1,6,2,12,4,24,8,48,16,5,30,10,3,18,108,36,216,72,432,144,864,288,96,

%T 32,192,64,21,7,42,14,84,28,9,54,324,1944,648,3888,1296,7776,2592,

%U 15552,5184,1728,576,3456,1152,384,128,768,256,85,510

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

%H Ivan Neretin, <a href="/A050088/b050088.txt">Table of n, a(n) for n = 1..10000</a>

%t Rest@Nest[Append[#, If[FreeQ[#, r = Quotient[#[[-1]], 3]], r, 6 #[[-1]]]] &, {0, 1}, 52] (* _Ivan Neretin_, Jul 31 2016 *)

%o (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

%Y Cf. A050000 and references therein.

%K nonn

%O 1,2

%A _Clark Kimberling_