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A316796 Number of unlabeled rooted trees with n nodes where the multiplicities in the multiset of branches under any given node are distinct. 4
1, 1, 2, 3, 6, 11, 21, 40, 75, 139, 263, 498, 932, 1761, 3322, 6244, 11775, 22204, 41810, 78795, 148458, 279690, 527006, 993033, 1870881 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

The a(6) = 11 trees:

(((((o)))))

((((oo))))

(((ooo)))

(((o)(o)))

((oo(o)))

((oooo))

(oo((o)))

(oo(oo))

(o(o)(o))

(ooo(o))

(ooooo)

MATHEMATICA

strut[n_]:=strut[n]=If[n===1, {{}}, Select[Join@@Function[c, Union[Sort/@Tuples[strut/@c]]]/@IntegerPartitions[n-1], UnsameQ@@Length/@Split[#]&]];

Table[Length[strut[n]], {n, 10}]

CROSSREFS

Cf. A000081, A004111, A130091, A316793, A316794, A316795.

Sequence in context: A092684 A123915 A132832 * A079116 A109222 A191789

Adjacent sequences:  A316793 A316794 A316795 * A316797 A316798 A316799

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Jul 14 2018

STATUS

approved

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Last modified March 21 01:18 EDT 2019. Contains 321356 sequences. (Running on oeis4.)