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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.

A360045 a(n) = Sum_{k=0..floor(n/3)} binomial(n+2,3*k+2) * Catalan(k).

Table of values

n a(n)
0 1
1 3
2 6
3 11
4 21
5 42
6 86
7 180
8 387
9 852
10 1908
11 4329
12 9933
13 23013
14 53748
15 126386
16 298953
17 710847
18 1698086
19 4073181
20 9806565
21 23689555
22 57401322
23 139475190
24 339767545
25 829638396
26 2030206248
27 4978136133
28 12229451631
29 30095772966
30 74184390468
31 183139941384

List of values

[1, 3, 6, 11, 21, 42, 86, 180, 387, 852, 1908, 4329, 9933, 23013, 53748, 126386, 298953, 710847, 1698086, 4073181, 9806565, 23689555, 57401322, 139475190, 339767545, 829638396, 2030206248, 4978136133, 12229451631, 30095772966, 74184390468, 183139941384]

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

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