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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 6 |
| 6 | 18 |
| 7 | 42 |
| 8 | 84 |
| 9 | 151 |
| 10 | 252 |
| 11 | 396 |
| 12 | 594 |
| 13 | 858 |
| 14 | 1201 |
| 15 | 1638 |
| 16 | 2184 |
| 17 | 2856 |
| 18 | 3672 |
| 19 | 4651 |
| 20 | 5814 |
| 21 | 7182 |
| 22 | 8778 |
| 23 | 10626 |
| 24 | 12751 |
| 25 | 15180 |
| 26 | 17940 |
| 27 | 21060 |
| 28 | 24570 |
| 29 | 28501 |
| 30 | 32886 |
| 31 | 37758 |
| 32 | 43152 |
| 33 | 49104 |
| 34 | 55651 |
| 35 | 62832 |
| 36 | 70686 |
| 37 | 79254 |
| 38 | 88578 |
| 39 | 98701 |
[0,0,0,0,1,6,18,42,84,151,252,396,594,858,1201, 1638,2184,2856,3672,4651,5814,7182,8778,10626, 12751,15180,17940,21060,24570,28501,32886,37758, 43152,49104,55651,62832,70686,79254,88578,98701] |