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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.

A375307 a(n) = Sum_{k=0..floor(3*n/5)} binomial(3*n-3*k,2*k).

Table of values

n a(n)
0 1
1 1
2 4
3 16
4 52
5 194
6 685
7 2452
8 8771
9 31327
10 112004
11 400285
12 1430710
13 5113647
14 18277014
15 65325542
16 233485250
17 834519021
18 2982723523
19 10660798289
20 38103641048
21 136189372297
22 486765693153
23 1739789499591
24 6218325456983
25 22225431015537
26 79437750107600

List of values

[1, 1, 4, 16, 52, 194, 685, 2452, 8771, 31327, 112004, 400285, 1430710, 5113647, 18277014, 65325542, 233485250, 834519021, 2982723523, 10660798289, 38103641048, 136189372297, 486765693153, 1739789499591, 6218325456983, 22225431015537, 79437750107600]

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

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