A182216 - OEIS

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A182216 as a simple table

n	a(n)
0	1
1	1
2	2
3	6
4	24
5	116
6	634
7	3762
8	23638
9	154816
10	1046010
11	7239440
12	51069582
13	365879686
14	2654987356
15	19473381290
16	144138193538
17	1075285161294
18	8076634643892
19	61028985689976
20	463596673890280
21	3538275218777642

[1,1,2,6,24,116,634,3762,23638,154816,1046010, 7239440,51069582,365879686,2654987356,19473381290, 144138193538,1075285161294,8076634643892, 61028985689976,463596673890280,3538275218777642]