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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 51 |
| 4 | 492 |
| 5 | 2500 |
| 6 | 8925 |
| 7 | 25431 |
| 8 | 61936 |
| 9 | 134352 |
| 10 | 266625 |
| 11 | 493075 |
| 12 | 861036 |
| 13 | 1433796 |
| 14 | 2293837 |
| 15 | 3546375 |
| 16 | 5323200 |
| 17 | 7786816 |
| 18 | 11134881 |
| 19 | 15604947 |
| 20 | 21479500 |
| 21 | 29091300 |
| 22 | 38829021 |
| 23 | 51143191 |
| 24 | 66552432 |
| 25 | 85650000 |
| 26 | 109110625 |
| 27 | 137697651 |
| 28 | 172270476 |
| 29 | 213792292 |
| 30 | 263338125 |
[0,1,51,492,2500,8925,25431,61936,134352,266625, 493075,861036,1433796,2293837,3546375,5323200, 7786816,11134881,15604947,21479500,29091300, 38829021,51143191,66552432,85650000,109110625, 137697651,172270476,213792292,263338125] |