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A192520 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 5 is in S. 2
5, 12, 30, 72, 75, 180, 187, 432, 450, 467, 1080, 1122, 1125, 1167, 2592, 2700, 2802, 2805, 2812, 2917, 6480, 6732, 6750, 7002, 7005, 7012, 7030, 7292, 15552, 16200, 16812, 16830, 16872, 16875, 17484, 17502, 17505, 17512, 17530, 17575, 18230 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..41.

MATHEMATICA

start = {5}; 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}]]]], # <

      70000 &]];

t = NestList[b, start, 14][[-1]] (* A192520 *)

Table[t[[i]] - t[[i - 1]], {i, 2, Length[t]}]  (* difference sequence *)

CROSSREFS

Cf. A192476.

Sequence in context: A009412 A009428 A220029 * A094125 A015625 A038357

Adjacent sequences:  A192517 A192518 A192519 * A192521 A192522 A192523

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jul 03 2011

STATUS

approved

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Last modified October 28 04:43 EDT 2021. Contains 348313 sequences. (Running on oeis4.)