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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.

A360168 a(n) = Sum_{k=0..floor(n/3)} binomial(2*n,n-3*k).

Table of values

n a(n)
0 1
1 2
2 6
3 21
4 78
5 297
6 1145
7 4447
8 17358
9 68001
10 267141
11 1051767
12 4148281
13 16385111
14 64797543
15 256515731
16 1016368078
17 4030114641
18 15990813773
19 63485616391
20 252175202373
21 1002136689071
22 3984080489263
23 15844839393411
24 63036297959993
25 250855287692647

List of values

[1, 2, 6, 21, 78, 297, 1145, 4447, 17358, 68001, 267141, 1051767, 4148281, 16385111, 64797543, 256515731, 1016368078, 4030114641, 15990813773, 63485616391, 252175202373, 1002136689071, 3984080489263, 15844839393411, 63036297959993, 250855287692647]

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

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