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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 70 |
| 5 | 708 |
| 6 | 15224 |
| 7 | 544152 |
| 8 | 39576432 |
| 9 | 5074417616 |
| 10 | 1296033011648 |
| 11 | 604178966756320 |
| 12 | 556052774253161600 |
| 13 | 954895322019762585664 |
| 14 | 3224152068625567826724224 |
| 15 | 20610090531322819956330186112 |
[1,3,10,70,708,15224,544152,39576432,5074417616, 1296033011648,604178966756320,556052774253161600, 954895322019762585664,3224152068625567826724224, 20610090531322819956330186112] |