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A050100
a(n) = floor(a(n-1)/3) if this is positive and not yet in the sequence, otherwise a(n) = 10*a(n-1).
5
1, 10, 3, 30, 300, 100, 33, 11, 110, 36, 12, 4, 40, 13, 130, 43, 14, 140, 46, 15, 5, 50, 16, 160, 53, 17, 170, 56, 18, 6, 2, 20, 200, 66, 22, 7, 70, 23, 230, 76, 25, 8, 80, 26, 260, 86, 28, 9, 90, 900, 9000, 3000, 1000, 333, 111, 37, 370
OFFSET
1,2
LINKS
MATHEMATICA
Rest@Nest[Append[#, If[FreeQ[#, r = Quotient[#[[-1]], 3]], r, 10 #[[-1]]]] &, {0, 1}, 56] (* Ivan Neretin, Jul 31 2016 *)
PROG
(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]=10*v[i-1]; next); for(j=1, i-1, if(v[j]==t, v[i]=10*v[i-1]; next(2))); v[i]=t); v \\ Charles R Greathouse IV, Jul 31 2016
CROSSREFS
Cf. A050000 and references therein.
Sequence in context: A243239 A079670 A343563 * A103219 A260680 A111126
KEYWORD
nonn
STATUS
approved