A043583 Numbers whose base-3 representation has exactly 3 runs.

10, 11, 15, 16, 19, 20, 21, 23, 28, 29, 31, 35, 37, 38, 42, 43, 45, 49, 51, 52, 55, 56, 58, 62, 63, 66, 68, 71, 73, 74, 75, 77, 82, 83, 85, 89, 94, 107, 109, 110, 112, 116, 118, 119, 123, 124, 126, 130, 132, 133, 135, 148, 153, 157, 159

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

F:= proc(d) local P;
  P:= [[1, 0, 1], [1, 0, 2], [1, 2, 0], [1, 2, 1], [2, 0, 1], [2, 0, 2], [2, 1, 0], [2, 1, 2]];
  P:= map(t -> seq(seq([t[1]$i, t[2]$j, t[3]$(d-i-j)], j=1..d-i-1), i=1..d-2), P);
  op(sort(map(t -> add(t[-i]*3^(i-1), i=1..d), P)))
end proc:
seq(F(d), d=3..5); # Robert Israel, Apr 29 2025

Mathematica

Select[Range[200], Length[Split[IntegerDigits[#, 3]]]==3&]  (* Harvey P. Dale, Jun 11 2024 *)

Crossrefs

Cf. A007089, A043584 (4 runs).

Subsequence of A043783 and A043794 and A043801.

Sequence in context: A244283 A373615 A373617 * A043773 A043779 A043783

Adjacent sequences: A043580 A043581 A043582 * A043584 A043585 A043586

Keyword

nonn,base,look

Author

Clark Kimberling

Status

approved