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A001811 as a simple table

na(n)
41
525
6450
77350
8117600
91905120
1031752000
11548856000
129879408000
13185513328000
143636061228800
1574373979680000
161586644899840000
1735272336619520000
18816302647480320000
1919645683716026368000
20491142092900659200000
2112740803704070041600000

[1,25,450,7350,117600,1905120,31752000,548856000,
 9879408000,185513328000,3636061228800,
 74373979680000,1586644899840000,35272336619520000,
 816302647480320000,19645683716026368000,
 491142092900659200000,12740803704070041600000]