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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 27 |
| 5 | 183 |
| 6 | 1143 |
| 7 | 6951 |
| 8 | 41895 |
| 9 | 251751 |
| 10 | 1511271 |
| 11 | 9069159 |
| 12 | 54418023 |
| 13 | 326514279 |
| 14 | 1959097959 |
| 15 | 11754612327 |
| 16 | 70527723111 |
| 17 | 423166436967 |
| 18 | 2538998818407 |
| 19 | 15233993303655 |
| 20 | 91403960608359 |
| 21 | 548423765223015 |
| 22 | 3290542594483815 |
| 23 | 19743255573194343 |
| 24 | 118459533451748967 |
[0,0,0,3,27,183,1143,6951,41895,251751,1511271, 9069159,54418023,326514279,1959097959,11754612327, 70527723111,423166436967,2538998818407, 15233993303655,91403960608359,548423765223015, 3290542594483815,19743255573194343, 118459533451748967] |