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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 6 |
| 5 | 10 |
| 6 | 375 |
| 7 | 2541 |
| 8 | 11788 |
| 9 | 317556 |
| 10 | 4238685 |
| 11 | 37921015 |
| 12 | 909616026 |
| 13 | 18283276518 |
| 14 | 261259582675 |
| 15 | 6360432558585 |
| 16 | 164704011195480 |
| 17 | 3332419310132776 |
| 18 | 88606184592031353 |
| 19 | 2713050497589230763 |
| 20 | 71412977041725823750 |
| 21 | 2144089948615678382970 |
[0,0,0,3,6,10,375,2541,11788,317556,4238685, 37921015,909616026,18283276518,261259582675, 6360432558585,164704011195480,3332419310132776, 88606184592031353,2713050497589230763, 71412977041725823750,2144089948615678382970] |