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A228939 Nodes of tree generated as follows: (1,2) is an edge, and if (x,y) is an edge, then (y,x*y) and (y,x^2 + y^2) are edges. 1
1, 2, 4, 5, 8, 10, 16, 20, 29, 32, 50, 68, 80, 125, 128, 145, 256, 320, 416, 500, 544, 640, 866, 1088, 1250, 1600, 2048, 2600, 4205, 4688, 5120, 6464, 6800, 8192, 8320, 15725, 16640, 21866, 25000, 25114, 34816, 36992, 51200, 66560, 102656, 128000, 130000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..47.

EXAMPLE

Taking the first generation of edges to be G(1) = {(1,2)}, the edge (1,2) grows G(2) = {(2,2), (2,5)}, which grows G(3) = {(2,4), (2,8), (5,10), (5,29)}, ... Expelling duplicate nodes and sorting leave (1, 2, 4, 5, 8, 10, 16, 20, 29, 32,...).

MATHEMATICA

f[x_, y_] := {{y, x* y}, {y, x^2 + y^2}}; x = 1; y = 2; t = {{x, y}};

u = Table[t = Flatten[Map[Apply[f, #] &, t], 1], {18}]; v = Flatten[u];

w = Flatten[Prepend[Table[v[[2 k]], {k, 1, Length[v]/2}], {x, y}]];

Sort[Union[w]]

CROSSREFS

Cf. A228853, A228939.

Sequence in context: A133020 A133075 A018433 * A115831 A094958 A018565

Adjacent sequences:  A228936 A228937 A228938 * A228940 A228941 A228942

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Sep 08 2013

STATUS

approved

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Last modified April 22 04:39 EDT 2019. Contains 322329 sequences. (Running on oeis4.)