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A013989 as a simple table

n a(n)
0 1
1 2
2 6
3 16
4 50
5 156
6 532
7 1856
8 6876
9 26200
10 104456
11 428352
12 1821976
13 7959056
14 35857200
15 165592576
16 785514512
17 3812387616
18 18948962656
19 96194028800
20 498931946016
21 2638959243712
22 14234346694976

[1,2,6,16,50,156,532,1856,6876,26200,104456,
 428352,1821976,7959056,35857200,165592576,
 785514512,3812387616,18948962656,96194028800,
 498931946016,2638959243712,14234346694976]

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Last modified December 14 05:36 EST 2019. Contains 329978 sequences. (Running on oeis4.)