A020086 - OEIS

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A020086 as a simple table

n	a(n)
0	1
1	0
2	1
3	3
4	13
5	64
6	369
7	2495
8	19338
9	169214
10	1649843
11	17735822
12	208395915
13	2657047923
14	36534408953
15	538882532060
16	8487399879954
17	142163947989232
18	2523410076808876
19	47313938940166438
20	934450294068287157

[1,0,1,3,13,64,369,2495,19338,169214,1649843, 17735822,208395915,2657047923,36534408953, 538882532060,8487399879954,142163947989232, 2523410076808876,47313938940166438, 934450294068287157]