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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |
| 3 | 20 |
| 4 | 23 |
| 5 | 66 |
| 6 | 947 |
| 7 | 1960 |
| 8 | 2907 |
| 9 | 19402 |
| 10 | 22309 |
| 11 | 64020 |
| 12 | 918589 |
| 13 | 1901198 |
| 14 | 2819787 |
| 15 | 18819920 |
| 16 | 21639707 |
| 17 | 62099334 |
| 18 | 891030383 |
| 19 | 1844160100 |
| 20 | 2735190483 |
| 21 | 18255302998 |
| 22 | 20990493481 |
| 23 | 60236289960 |
| 24 | 864298552921 |
| 25 | 1788833395802 |
| 26 | 2653131948723 |
| 27 | 17707625088140 |
[1,2,3,20,23,66,947,1960,2907,19402,22309,64020, 918589,1901198,2819787,18819920,21639707,62099334, 891030383,1844160100,2735190483,18255302998, 20990493481,60236289960,864298552921, 1788833395802,2653131948723,17707625088140] |