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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.

A371774 a(n) = Sum_{k=0..floor(n/3)} binomial(3*n-k+1,n-3*k).

Table of values

n a(n)
0 1
1 4
2 21
3 121
4 727
5 4473
6 27949
7 176549
8 1124332
9 7205511
10 46411744
11 300183757
12 1948255421
13 12681654613
14 82755728730
15 541213820732
16 3546268982757
17 23276100962571
18 153004515241866
19 1007131032951572
20 6637396253259291
21 43791520333601111

List of values

[1, 4, 21, 121, 727, 4473, 27949, 176549, 1124332, 7205511, 46411744, 300183757, 1948255421, 12681654613, 82755728730, 541213820732, 3546268982757, 23276100962571, 153004515241866, 1007131032951572, 6637396253259291, 43791520333601111]

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

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