A178222 - OEIS

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A178222 as a simple table

n	a(n)
1	0
2	2
3	8
4	28
5	88
6	270
7	816
8	2456
9	7376
10	22138
11	66424
12	199284
13	597864
14	1793606
15	5380832
16	16142512
17	48427552
18	145282674
19	435848040
20	1307544140
21	3922632440
22	11767897342
23	35303692048
24	105911076168
25	317733228528

[0,2,8,28,88,270,816,2456,7376,22138,66424,199284, 597864,1793606,5380832,16142512,48427552, 145282674,435848040,1307544140,3922632440, 11767897342,35303692048,105911076168,317733228528]