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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.

A331933 Number of semi-lone-child-avoiding rooted trees with at most one distinct non-leaf branch directly under any vertex.

Table of values

n a(n)
1 1
2 1
3 1
4 2
5 4
6 6
7 12
8 18
9 33
10 52
11 90
12 142
13 242
14 384
15 639
16 1028
17 1688
18 2716
19 4445
20 7161
21 11665
22 18839
23 30595
24 49434
25 80199
26 129637
27 210079
28 339750
29 550228
30 889978
31 1440909
32 2330887
33 3772845
34 6103823
35 9878357
36 15982196
37 25863454
38 41845650
39 67713550
40 109559443

List of values

[1, 1, 1, 2, 4, 6, 12, 18, 33, 52, 90, 142, 242, 384, 639, 1028, 1688, 2716, 4445, 7161, 11665, 18839, 30595, 49434, 80199, 129637, 210079, 339750, 550228, 889978, 1440909, 2330887, 3772845, 6103823, 9878357, 15982196, 25863454, 41845650, 67713550, 109559443]

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

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