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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A155520 Triangle read by rows: A(n,k) is the number of ordered trees with n edges having k drawings. A drawing of an ordered tree T with n edges is a sequence of trees (T_0, T_1, T_2, ..., T_n), such that T_n = T and T_{i-1} arises from T_i by deleting a leaf of T_i.

Table of values

n a(n)
1 1
2 2
3 3
4 2
5 4
6 2
7 6
8 1
9 1
10 5
11 2
12 6
13 9
14 1
15 4
16 4
17 4
18 2
19 1
20 2
21 2

List of values

[1, 2, 3, 2, 4, 2, 6, 1, 1, 5, 2, 6, 9, 1, 4, 4, 4, 2, 1, 2, 2]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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