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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 44 |
| 2 | 870 |
| 3 | 9480 |
| 4 | 68290 |
| 5 | 365936 |
| 6 | 1573374 |
| 7 | 5709120 |
| 8 | 18107760 |
| 9 | 51488800 |
| 10 | 133748186 |
| 11 | 321979164 |
| 12 | 726436425 |
| 13 | 1549758640 |
| 14 | 3148837580 |
| 15 | 6129352176 |
| 16 | 11486265339 |
| 17 | 20807609460 |
| 18 | 36563769670 |
| 19 | 62510325680 |
| 20 | 104239453956 |
| 21 | 169923049824 |
| 22 | 271300238650 |
| 23 | 424972948400 |
[1,44,870,9480,68290,365936,1573374,5709120, 18107760,51488800,133748186,321979164,726436425, 1549758640,3148837580,6129352176,11486265339, 20807609460,36563769670,62510325680,104239453956, 169923049824,271300238650,424972948400] |