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| n | a(n) |
|---|---|
| 9 | 1 |
| 10 | 18 |
| 11 | 180 |
| 12 | 1311 |
| 13 | 7740 |
| 14 | 39204 |
| 15 | 176388 |
| 16 | 721530 |
| 17 | 2728053 |
| 18 | 9651056 |
| 19 | 32246892 |
| 20 | 102515508 |
| 21 | 311923386 |
| 22 | 912771468 |
| 23 | 2579132196 |
| 24 | 7060677537 |
| 25 | 18781247700 |
| 26 | 48660380190 |
| 27 | 123061973176 |
| 28 | 304351869708 |
| 29 | 737293187286 |
| 30 | 1752035386188 |
| 31 | 4089222211212 |
| 32 | 9384936015492 |
| 33 | 21201250825554 |
[1,18,180,1311,7740,39204,176388,721530,2728053, 9651056,32246892,102515508,311923386,912771468, 2579132196,7060677537,18781247700,48660380190, 123061973176,304351869708,737293187286, 1752035386188,4089222211212,9384936015492, 21201250825554] |