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A121198 as a simple table

n a(n)
1 2
2 1
3 4
4 10
5 36
6 110
7 392
8 1371
9 5000
10 18251
11 67792
12 253040
13 952540
14 3602846
15 13699554
16 52298057
17 200406388
18 770416390
19 2970401696
20 11482413680
21 4449188109

[2,1,4,10,36,110,392,1371,5000,18251,67792,253040,
 952540,3602846,13699554,52298057,200406388,
 770416390,2970401696,11482413680,4449188109]

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Last modified December 15 08:47 EST 2018. Contains 318147 sequences. (Running on oeis4.)