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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 30 |
| 4 | 220 |
| 5 | 950 |
| 6 | 3045 |
| 7 | 8036 |
| 8 | 18480 |
| 9 | 38340 |
| 10 | 73425 |
| 11 | 131890 |
| 12 | 224796 |
| 13 | 366730 |
| 14 | 576485 |
| 15 | 877800 |
| 16 | 1300160 |
| 17 | 1879656 |
| 18 | 2659905 |
| 19 | 3693030 |
| 20 | 5040700 |
| 21 | 6775230 |
| 22 | 8980741 |
| 23 | 11754380 |
| 24 | 15207600 |
| 25 | 19467500 |
| 26 | 24678225 |
| 27 | 31002426 |
| 28 | 38622780 |
| 29 | 47743570 |
[0,1,30,220,950,3045,8036,18480,38340,73425, 131890,224796,366730,576485,877800,1300160, 1879656,2659905,3693030,5040700,6775230,8980741, 11754380,15207600,19467500,24678225,31002426, 38622780,47743570] |