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A007661 as a simple table

na(n)
01
11
22
33
44
510
618
728
880
9162
10280
11880
121944
133640
1412320
1529160
1658240
17209440
18524880
191106560
204188800
2111022480
2224344320
2396342400
24264539520
25608608000
262504902400
277142567040
2817041024000
2972642169600
30214277011200
31528271744000
322324549427200

[1,1,2,3,4,10,18,28,80,162,280,880,1944,3640,
 12320,29160,58240,209440,524880,1106560,4188800,
 11022480,24344320,96342400,264539520,608608000,
 2504902400,7142567040,17041024000,72642169600,
 214277011200,528271744000,2324549427200]