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A124346
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Number of rooted identity trees on n nodes with thinning limbs.
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5
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1, 1, 1, 2, 2, 4, 6, 11, 17, 32, 56, 102, 184, 340, 624, 1161, 2156, 4036, 7562, 14234, 26828, 50747, 96125, 182545, 347187, 661618, 1262583, 2413275, 4618571, 8850905, 16981142, 32616900, 62713951, 120703497, 232527392, 448344798, 865182999, 1670884073
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OFFSET
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1,4
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COMMENTS
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A rooted tree with thinning limbs is such that if a node has k children, all its children have at most k children.
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LINKS
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EXAMPLE
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The a(7) = 6 trees are ((((((o)))))), (o((((o))))), (o(o((o)))), ((o)(((o)))), ((o)(o(o))), (o(o)((o))). - Gus Wiseman, Jan 25 2018
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MATHEMATICA
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idthinQ[t_]:=And@@Cases[t, b_List:>UnsameQ@@b&&Length[b]>=Max@@Length/@b, {0, Infinity}];
itrut[n_]:=itrut[n]=If[n===1, {{}}, Select[Join@@Function[c, Union[Sort/@Tuples[itrut/@c]]]/@IntegerPartitions[n-1], idthinQ]];
Table[Length[itrut[n]], {n, 25}] (* Gus Wiseman, Jan 25 2018 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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