A013227 - OEIS

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A013227 as a simple table

n	a(n)
0	0
1	0
2	-1
3	1
4	-6
5	15
6	-135
7	600
8	-6580
9	42805
10	-546525
11	4698450
12	-68473350
13	732163575
14	-12012875875
15	153571600000
16	-2805371985000
17	41710773599625
18	-840435196901625
19	14241298404498750
20	-313987574315496250

[0,0,-1,1,-6,15,-135,600,-6580,42805,-546525, 4698450,-68473350,732163575,-12012875875, 153571600000,-2805371985000,41710773599625, -840435196901625,14241298404498750, -313987574315496250]