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.

A120429 Triangle read by rows: T(n,k) is the number of ternary trees with n edges and having k leaves (i.e., vertices of degree 0; n>=0, k>=1). A ternary tree is a rooted tree in which each vertex has at most three children and each child of a vertex is designated as its left or middle or right child.

Table of values

n a(n)
0 1
1 3
2 9
3 3
4 27
5 27
6 1
7 81
8 162
9 30
10 243
11 810
12 360
13 15
14 729
15 3645
16 2970
17 405
18 3
19 2187
20 15309
21 19845
22 5670
23 252
24 6561
25 61236
26 115668
27 56700
28 6426
29 84
30 19683
31 236196
32 612360
33 459270
34 98658
35 4536
36 12
37 59049
38 885735
39 3018060
40 3214890
41 1122660

List of values

[1, 3, 9, 3, 27, 27, 1, 81, 162, 30, 243, 810, 360, 15, 729, 3645, 2970, 405, 3, 2187, 15309, 19845, 5670, 252, 6561, 61236, 115668, 56700, 6426, 84, 19683, 236196, 612360, 459270, 98658, 4536, 12, 59049, 885735, 3018060, 3214890, 1122660]

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

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