cp's OEIS Frontend

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.

A143363 Number of ordered trees with n edges and having no protected vertices. A protected vertex in an ordered tree is a vertex at least 2 edges away from its leaf descendants.

Table of values

n a(n)
0 1
1 1
2 1
3 3
4 6
5 17
6 43
7 123
8 343
9 1004
10 2938
11 8791
12 26456
13 80597
14 247091
15 763507
16 2372334
17 7413119
18 23271657
19 73376140
20 232238350
21 737638868
22 2350318688
23 7510620143
24 24064672921
25 77294975952
26 248832007318
27 802737926643

List of values

[1, 1, 1, 3, 6, 17, 43, 123, 343, 1004, 2938, 8791, 26456, 80597, 247091, 763507, 2372334, 7413119, 23271657, 73376140, 232238350, 737638868, 2350318688, 7510620143, 24064672921, 77294975952, 248832007318, 802737926643]

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

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