A192519 - OEIS

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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.

2

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

(list; graph; refs; listen; history; text; internal format)

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

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