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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 10 |
| 6 | 20 |
| 7 | 40 |
| 8 | 70 |
| 9 | 112 |
| 10 | 168 |
| 11 | 252 |
| 12 | 360 |
| 13 | 495 |
| 14 | 660 |
| 15 | 880 |
| 16 | 1144 |
| 17 | 1456 |
| 18 | 1820 |
| 19 | 2275 |
| 20 | 2800 |
| 21 | 3400 |
| 22 | 4080 |
| 23 | 4896 |
| 24 | 5814 |
| 25 | 6840 |
| 26 | 7980 |
| 27 | 9310 |
| 28 | 10780 |
| 29 | 12397 |
| 30 | 14168 |
| 31 | 16192 |
| 32 | 18400 |
| 33 | 20800 |
| 34 | 23400 |
| 35 | 26325 |
| 36 | 29484 |
| 37 | 32886 |
| 38 | 36540 |
| 39 | 40600 |
| 40 | 44950 |
[0,0,1,4,10,20,40,70,112,168,252,360,495,660,880, 1144,1456,1820,2275,2800,3400,4080,4896,5814,6840, 7980,9310,10780,12397,14168,16192,18400,20800, 23400,26325,29484,32886,36540,40600,44950] |