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A002698 as a simple table

na(n)
21
318
4160
51120
66912
739424
8212992
91105920
105570560
1127394048
12132120576
13627048448
142936012800
1513589544960
1662277025792
17282930970624
181275605286912
195712306503680
2025426206392320
21112562502893568
22495879744126976
232174833999740928
249499780463984640

[1,18,160,1120,6912,39424,212992,1105920,5570560,
 27394048,132120576,627048448,2936012800,
 13589544960,62277025792,282930970624,
 1275605286912,5712306503680,25426206392320,
 112562502893568,495879744126976,2174833999740928,
 9499780463984640]