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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 9 |
| 4 | 60 |
| 5 | 250 |
| 6 | 765 |
| 7 | 1911 |
| 8 | 4144 |
| 9 | 8100 |
| 10 | 14625 |
| 11 | 24805 |
| 12 | 39996 |
| 13 | 61854 |
| 14 | 92365 |
| 15 | 133875 |
| 16 | 189120 |
| 17 | 261256 |
| 18 | 353889 |
| 19 | 471105 |
| 20 | 617500 |
| 21 | 798210 |
| 22 | 1018941 |
| 23 | 1285999 |
| 24 | 1606320 |
| 25 | 1987500 |
| 26 | 2437825 |
| 27 | 2966301 |
| 28 | 3582684 |
| 29 | 4297510 |
| 30 | 5122125 |
| 31 | 6068715 |
| 32 | 7150336 |
| 33 | 8380944 |
| 34 | 9775425 |
| 35 | 11349625 |
| 36 | 13120380 |
| 37 | 15105546 |
| 38 | 17324029 |
| 39 | 19795815 |
| 40 | 22542000 |
[0,1,9,60,250,765,1911,4144,8100,14625,24805, 39996,61854,92365,133875,189120,261256,353889, 471105,617500,798210,1018941,1285999,1606320, 1987500,2437825,2966301,3582684,4297510,5122125, 6068715,7150336,8380944,9775425,11349625,13120380, 15105546,17324029,19795815,22542000] |