A068641 - OEIS

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A068641 as a simple table

n	a(n)
1	1
2	55
3	171
4	3003
5	15051
6	617716
7	1269621
8	35133153
9	178727871
10	1264114621
11	13953435931
12	0
13	1313207023131
14	19895044059891
15	114401848104411
16	1250444114440521
17	11121736463712111
18	357961407704169753

[1,55,171,3003,15051,617716,1269621,35133153, 178727871,1264114621,13953435931,0,1313207023131, 19895044059891,114401848104411,1250444114440521, 11121736463712111,357961407704169753]