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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.

A378407 a(n) = Sum_{k=0..floor(n/3)} binomial(n,k) * binomial(n+2*k,n-3*k).

Table of values

n a(n)
0 1
1 1
2 1
3 4
4 25
5 106
6 352
7 1114
8 3865
9 14539
10 54886
11 201763
12 732568
13 2679535
14 9917818
15 36903049
16 137265337
17 510201961
18 1898730307
19 7082472358
20 26468394430
21 99026247688
22 370771000975
23 1389387381691
24 5211329801272
25 19564292736706
26 73504888190371
27 276350941918741

List of values

[1, 1, 1, 4, 25, 106, 352, 1114, 3865, 14539, 54886, 201763, 732568, 2679535, 9917818, 36903049, 137265337, 510201961, 1898730307, 7082472358, 26468394430, 99026247688, 370771000975, 1389387381691, 5211329801272, 19564292736706, 73504888190371, 276350941918741]

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

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