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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 14 |
| 4 | 168 |
| 5 | 3147 |
| 6 | 90563 |
| 7 | 3561231 |
| 8 | 185790622 |
| 9 | 12599020184 |
| 10 | 1071164190670 |
| 11 | 111813313594259 |
| 12 | 14140296360430353 |
| 13 | 2132273568722682621 |
| 14 | 378197030144360862958 |
| 15 | 78127192632748956075174 |
| 16 | 18627308660113953164384812 |
| 17 | 5081218748742336002185874439 |
| 18 | 1574128413278644602881499193579 |
[1,1,2,14,168,3147,90563,3561231,185790622, 12599020184,1071164190670,111813313594259, 14140296360430353,2132273568722682621, 378197030144360862958,78127192632748956075174, 18627308660113953164384812, 5081218748742336002185874439, 1574128413278644602881499193579] |