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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 31 |
| 3 | 252 |
| 4 | 2113 |
| 5 | 17684 |
| 6 | 147920 |
| 7 | 1237439 |
| 8 | 10351593 |
| 9 | 86594795 |
| 10 | 724396370 |
| 11 | 6059833949 |
| 12 | 50692672540 |
| 13 | 424062286786 |
| 14 | 3547432284249 |
| 15 | 29675536361423 |
| 16 | 248246446379403 |
| 17 | 2076670068892280 |
| 18 | 17372085836189001 |
| 19 | 145323694322280832 |
[3,31,252,2113,17684,147920,1237439,10351593, 86594795,724396370,6059833949,50692672540, 424062286786,3547432284249,29675536361423, 248246446379403,2076670068892280, 17372085836189001,145323694322280832] |