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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 69 |
| 4 | 497 |
| 5 | 3471 |
| 6 | 23913 |
| 7 | 163843 |
| 8 | 1120361 |
| 9 | 7656486 |
| 10 | 52318487 |
| 11 | 357514990 |
| 12 | 2443171893 |
| 13 | 16696623338 |
| 14 | 114106843007 |
| 15 | 779828040814 |
| 16 | 5329516155813 |
| 17 | 36423140201867 |
| 18 | 248924239329266 |
| 19 | 1701206464309672 |
| 20 | 11626442430613559 |
| 21 | 79457820305840230 |
| 22 | 543033266143895110 |
[1,1,9,69,497,3471,23913,163843,1120361,7656486, 52318487,357514990,2443171893,16696623338, 114106843007,779828040814,5329516155813, 36423140201867,248924239329266,1701206464309672, 11626442430613559,79457820305840230, 543033266143895110] |