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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.

A278884 a(n) = binomial(3*n-1,n) * binomial(3*n,n)/(2*n+1).

Table of values

n a(n)
0 1
1 2
2 30
3 672
4 18150
5 546546
6 17672928
7 600935040
8 21212454582
9 770748371250
10 28657235757150
11 1085694550387200
12 41778588391394400
13 1628982594897249312
14 64234570537702934400
15 2557710564063135005184
16 102714012593435476016982
17 4155894894567674772785250
18 169274181059121504574121550
19 6935873114065443534326340000
20 285716428631735196825345889350
21 11826871503027977442890882704050
22 491714173272153004121882711232000

List of values

[1, 2, 30, 672, 18150, 546546, 17672928, 600935040, 21212454582, 770748371250, 28657235757150, 1085694550387200, 41778588391394400, 1628982594897249312, 64234570537702934400, 2557710564063135005184, 102714012593435476016982, 4155894894567674772785250, 169274181059121504574121550, 6935873114065443534326340000, 285716428631735196825345889350, 11826871503027977442890882704050, 491714173272153004121882711232000]

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

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