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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 36 |
| 4 | 136 |
| 5 | 477 |
| 6 | 1703 |
| 7 | 5746 |
| 8 | 19099 |
| 9 | 61622 |
| 10 | 195366 |
| 11 | 607069 |
| 12 | 1856516 |
| 13 | 5586870 |
| 14 | 16579850 |
| 15 | 48549116 |
| 16 | 140438966 |
| 17 | 401592524 |
| 18 | 1136121837 |
| 19 | 3181700219 |
| 20 | 8825733603 |
| 21 | 24261363403 |
| 22 | 66124058839 |
| 23 | 178757752892 |
| 24 | 479513547399 |
| 25 | 1276792213203 |
| 26 | 3375707760306 |
| 27 | 8864712158225 |
[1,1,9,36,136,477,1703,5746,19099,61622,195366, 607069,1856516,5586870,16579850,48549116, 140438966,401592524,1136121837,3181700219, 8825733603,24261363403,66124058839,178757752892, 479513547399,1276792213203,3375707760306, 8864712158225] |