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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 3 |
| 3 | 52 |
| 4 | 390 |
| 5 | 1860 |
| 6 | 6665 |
| 7 | 19608 |
| 8 | 49932 |
| 9 | 113880 |
| 10 | 238095 |
| 11 | 463980 |
| 12 | 853138 |
| 13 | 1494012 |
| 14 | 2509845 |
| 15 | 4068080 |
| 16 | 6391320 |
| 17 | 9769968 |
| 18 | 14576667 |
| 19 | 21282660 |
| 20 | 30476190 |
| 21 | 42883060 |
| 22 | 59389473 |
| 23 | 81067272 |
| 24 | 109201700 |
| 25 | 145321800 |
| 26 | 191233575 |
| 27 | 249056028 |
| 28 | 321260202 |
| 29 | 410711340 |
| 30 | 520714285 |
[0,0,3,52,390,1860,6665,19608,49932,113880,238095, 463980,853138,1494012,2509845,4068080,6391320, 9769968,14576667,21282660,30476190,42883060, 59389473,81067272,109201700,145321800,191233575, 249056028,321260202,410711340,520714285] |