A268658 - OEIS

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A268658 as a simple table

n	a(n)
1	2
2	8
3	18
4	66
5	189
6	209
7	408
8	2208
9	2816
10	3168
11	3912
12	20909
13	54792
14	59973
15	157169
16	303093
17	709968
18	801978
19	1832496
20	2145353
21	2291610
22	5082306
23	10829346
24	16408818

[2,8,18,66,189,209,408,2208,2816,3168,3912,20909, 54792,59973,157169,303093,709968,801978,1832496, 2145353,2291610,5082306,10829346,16408818]