A192522 Monotonic ordering of set S generated by these rules: if x and y are in S then floor((x-1)(y-1)/2) is in S, and 5 is in S.

5, 8, 14, 24, 26, 45, 46, 50, 80, 84, 87, 88, 90, 98, 149, 154, 157, 158, 162, 166, 171, 172, 174, 178, 194, 264, 276, 286, 287, 290, 292, 296, 301, 304, 306, 311, 312, 314, 318, 322, 330, 339, 340, 342, 346, 354, 386, 506, 513, 517, 518, 526, 535, 539

Offset: 1

Author

Clark Kimberling, Jul 03 2011

Keywords

• nonn

Crossrefs

Cf. A192476.

Programs

Mathematica

start = {5}; f[x_, y_] := Floor[(x - 1)*(y - 1)/2]
b[x_] :=
  Block[{w = x},
   Select[Union[
     Flatten[AppendTo[w,
       Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
      1500 &]];
t = NestList[b, start, 12][[-1]] (* A192522 *)
Table[t[[i]] - t[[i - 1]], {i, 2, Length[t]}]  (* differences *)