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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 4 |
| 5 | 10 |
| 6 | 20 |
| 7 | 35 |
| 8 | 1176 |
| 9 | 10164 |
| 10 | 58920 |
| 11 | 277365 |
| 12 | 4472380 |
| 13 | 69189406 |
| 14 | 772011604 |
| 15 | 6861855455 |
| 16 | 95279504880 |
| 17 | 1819310613800 |
| 18 | 30768119885136 |
| 19 | 430200439251369 |
| 20 | 6770486332450740 |
| 21 | 139958614722287410 |
| 22 | 3033142442978720380 |
| 23 | 58782387380290683571 |
| 24 | 1138026666874389737544 |
[0,0,0,0,4,10,20,35,1176,10164,58920,277365, 4472380,69189406,772011604,6861855455,95279504880, 1819310613800,30768119885136,430200439251369, 6770486332450740,139958614722287410, 3033142442978720380,58782387380290683571, 1138026666874389737544] |