A192519 Monotonic ordering of set S generated by these rules: if x and y are in S then floor(x*y/2) is in S, and 3 is in S.

3, 4, 6, 8, 9, 12, 13, 16, 18, 19, 24, 26, 27, 28, 32, 36, 38, 39, 40, 42, 48, 52, 54, 56, 57, 58, 60, 63, 64, 72, 76, 78, 80, 81, 84, 85, 87, 90, 94, 96, 104, 108, 112, 114, 116, 117, 120, 121, 123, 126, 127, 128, 130, 135, 141, 144, 152, 156, 160, 162, 168, 169

Offset

1,1

Links

Table of n, a(n) for n=1..62.

Mathematica

start = {3}; f[x_, y_] := Floor[x*y/2]
b[x_] :=
  Block[{w = x},
   Select[Union[
     Flatten[AppendTo[w,
       Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
      400 &]];
t = NestList[b, start, 12][[-1]] (* A192519 *)
Table[t[[i]] - t[[i - 1]], {i, 2, Length[t]}]

Crossrefs

Cf. A192476.

Sequence in context: A255773 A195019 A288601 * A036446 A284469 A366288

Adjacent sequences: A192516 A192517 A192518 * A192520 A192521 A192522

Keyword

nonn

Author

Clark Kimberling, Jul 03 2011

Status

approved