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A053505 as a simple table

na(n)
01
11
22
36
418
590
6540
73060
820700
9145980
101459800
1113854600
12140059800
131514748600
1415869034000
15285268878000
164109761962000
1759488383690000
18935767530036000
1913364309726748000
20240338216104020000
214540941256642020000
2279739974380153240000

[1,1,2,6,18,90,540,3060,20700,145980,1459800,
 13854600,140059800,1514748600,15869034000,
 285268878000,4109761962000,59488383690000,
 935767530036000,13364309726748000,
 240338216104020000,4540941256642020000,
 79739974380153240000]