A270099 - OEIS

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A270099 as a simple table

n	a(n)
0	1
1	4
2	40
3	196
4	844
5	3532
6	14784
7	60248
8	242792
9	977020
10	3920112
11	15702644
12	62855916
13	251527896
14	1006303768
15	4025613088

[1,4,40,196,844,3532,14784,60248,242792,977020, 3920112,15702644,62855916,251527896,1006303768, 4025613088]