A024432 - OEIS

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A024432 as a simple table

n	a(n)
1	1
2	0
3	3
4	1
5	20
6	41
7	147
8	1450
9	1441
10	27513
11	165814
12	166011
13	6759857
14	38623792
15	54257895
16	2366944123
17	16391013794
18	27871290287
19	1112444405811
20	11151033695300
21	24805899491473

[1,0,3,1,20,41,147,1450,1441,27513,165814,166011, 6759857,38623792,54257895,2366944123,16391013794, 27871290287,1112444405811,11151033695300, 24805899491473]