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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 25 |
| 3 | 120 |
| 4 | 420 |
| 5 | 1190 |
| 6 | 2898 |
| 7 | 6300 |
| 8 | 12540 |
| 9 | 23265 |
| 10 | 40755 |
| 11 | 68068 |
| 12 | 109200 |
| 13 | 169260 |
| 14 | 254660 |
| 15 | 373320 |
| 16 | 534888 |
| 17 | 750975 |
| 18 | 1035405 |
| 19 | 1404480 |
| 20 | 1877260 |
| 21 | 2475858 |
| 22 | 3225750 |
| 23 | 4156100 |
| 24 | 5300100 |
| 25 | 6695325 |
| 26 | 8384103 |
| 27 | 10413900 |
| 28 | 12837720 |
| 29 | 15714520 |
| 30 | 19109640 |
| 31 | 23095248 |
| 32 | 27750800 |
[0,3,25,120,420,1190,2898,6300,12540,23265,40755, 68068,109200,169260,254660,373320,534888,750975, 1035405,1404480,1877260,2475858,3225750,4156100, 5300100,6695325,8384103,10413900,12837720, 15714520,19109640,23095248,27750800] |