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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.

A069720 a(n) = 2^(n-1)*binomial(2*n-1, n).

Table of values

n a(n)
1 1
2 6
3 40
4 280
5 2016
6 14784
7 109824
8 823680
9 6223360
10 47297536
11 361181184
12 2769055744
13 21300428800
14 164317593600
15 1270722723840
16 9848101109760
17 76467608616960
18 594748067020800
19 4632774416793600
20 36135640450990080
21 282202144474398720
22 2206307674981662720
23 17266755717247795200

List of values

[1, 6, 40, 280, 2016, 14784, 109824, 823680, 6223360, 47297536, 361181184, 2769055744, 21300428800, 164317593600, 1270722723840, 9848101109760, 76467608616960, 594748067020800, 4632774416793600, 36135640450990080, 282202144474398720, 2206307674981662720, 17266755717247795200]

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

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