A188341 Numbers having no 0's and not more than one 1 in their representation in base 3.

1, 2, 5, 7, 8, 17, 23, 25, 26, 53, 71, 77, 79, 80, 161, 215, 233, 239, 241, 242, 485, 647, 701, 719, 725, 727, 728, 1457, 1943, 2105, 2159, 2177, 2183, 2185, 2186, 4373, 5831, 6317, 6479, 6533, 6551, 6557, 6559, 6560, 13121, 17495, 18953

Offset

1,2

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

V. Shevelev, Binomial Coefficient Predictors, Journal of Integer Sequences, Vol. 14 (2011), Article 11.2.8

Maple

a:= proc(n) option remember; local i, l, m, t;
      m:= `if`(n=1, 0, a(n-1));
      l:= NULL;
      for t while m>0 do l:= l, irem(m, 3, 'm') od;
      l:= array([l, 0]);
      for i while l[i]=2 do od;
      if l[i]=0 then l[i]:= 1
                else l[i]:= 2;
                     if i>1 then l[i-1]:= 1 fi
      fi;
      add(l[i] *3^(i-1), i=1..t)
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, Apr 02 2011

Mathematica

okQ[n_]:=DigitCount[n, 3, 0]==0&&DigitCount[n, 3, 1]<2; Select[Range[20000], okQ]  (* Harvey P. Dale, Apr 16 2011 *)

Crossrefs

Cf. A062756, A077267.

Sequence in context: A139481 A363626 A340326 * A238364 A342730 A227445

Adjacent sequences: A188338 A188339 A188340 * A188342 A188343 A188344

Keyword

nonn,base

Author

Vladimir Shevelev, Apr 02 2011

Status

approved