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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.

A339838 Number of rooted bicolored trees on n unlabeled nodes such that black nodes are not adjacent to each other and every white node is adjacent to a black node.

Table of values

n a(n)
1 1
2 2
3 4
4 10
5 27
6 75
7 221
8 662
9 2042
10 6402
11 20407
12 65828
13 214720
14 706600
15 2343767
16 7826752
17 26293468
18 88796471
19 301290197
20 1026595232
21 3511246069
22 12050780294
23 41488523002
24 143246116231
25 495881545520
26 1720771421470
27 5984652387281
28 20857113949868
29 72829214554641
30 254762923125929

List of values

[1, 2, 4, 10, 27, 75, 221, 662, 2042, 6402, 20407, 65828, 214720, 706600, 2343767, 7826752, 26293468, 88796471, 301290197, 1026595232, 3511246069, 12050780294, 41488523002, 143246116231, 495881545520, 1720771421470, 5984652387281, 20857113949868, 72829214554641, 254762923125929]

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

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