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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 4 |
| 3 | 18 |
| 4 | 60 |
| 5 | 140 |
| 6 | 330 |
| 7 | 630 |
| 8 | 1232 |
| 9 | 2160 |
| 10 | 3780 |
| 11 | 6160 |
| 12 | 10164 |
| 13 | 15756 |
| 14 | 24570 |
| 15 | 36960 |
| 16 | 55440 |
| 17 | 80784 |
| 18 | 117810 |
| 19 | 167580 |
| 20 | 238260 |
| 21 | 332640 |
| 22 | 462924 |
| 23 | 635030 |
| 24 | 869400 |
| 25 | 1174800 |
| 26 | 1583400 |
| 27 | 2113020 |
| 28 | 2810808 |
| 29 | 3706780 |
| 30 | 4875480 |
| 31 | 6363060 |
| 32 | 8282208 |
| 33 | 10711008 |
| 34 | 13811820 |
| 35 | 17710770 |
[0,0,4,18,60,140,330,630,1232,2160,3780,6160, 10164,15756,24570,36960,55440,80784,117810,167580, 238260,332640,462924,635030,869400,1174800, 1583400,2113020,2810808,3706780,4875480,6363060, 8282208,10711008,13811820,17710770] |