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A298478 Number of unlabeled rooted trees with n nodes in which all positive outdegrees are different. 2
1, 1, 1, 3, 3, 5, 13, 15, 23, 34, 95, 106, 176, 241, 374, 942, 1129, 1760, 2515, 3711, 5136, 12857, 14911, 23814, 33002, 49141, 65798, 97056, 209707, 255042, 389725, 545290, 790344, 1071010 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..34.

EXAMPLE

The a(7) = 13 trees: ((o(ooo))), ((oo(oo))), ((ooooo)), (o((ooo))), (o(oo(o))), (o(oooo)), ((o)(ooo)), (oo((oo))), (oo(o(o))), (o(o)(oo)), (ooo(oo)), (oooo(o)), (oooooo).

MATHEMATICA

krut[n_]:=krut[n]=If[n===1, {{}}, Select[Join@@Function[c, Union[Sort/@Tuples[krut/@c]]]/@IntegerPartitions[n-1], UnsameQ@@Length/@Cases[#, {__}, {0, Infinity}]&]];

Table[krut[n]//Length, {n, 15}]

CROSSREFS

Cf. A000081, A001190, A001678, A004111, A032305, A124343, A290689, A295461, A298118, A298304, A298422, A298479.

Sequence in context: A218426 A321662 A320176 * A144419 A212322 A226921

Adjacent sequences:  A298475 A298476 A298477 * A298479 A298480 A298481

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Jan 19 2018

EXTENSIONS

a(27)-a(34) from Robert G. Wilson v, Jan 19 2018

STATUS

approved

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Last modified November 13 20:57 EST 2019. Contains 329106 sequences. (Running on oeis4.)