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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 10 |
| 6 | 34 |
| 7 | 272 |
| 8 | 3528 |
| 9 | 97144 |
| 10 | 4870920 |
| 11 | 452016608 |
| 12 | 77054901728 |
| 13 | 24271105072736 |
| 14 | 14200712295904928 |
| 15 | 15510501136026729216 |
| 16 | 31765207922047709885696 |
| 17 | 122456389219489134370435456 |
| 18 | 891699423142395494501906828160 |
| 19 | 12302820585630191716774996205431296 |
[1,1,2,3,10,34,272,3528,97144,4870920,452016608, 77054901728,24271105072736,14200712295904928, 15510501136026729216,31765207922047709885696, 122456389219489134370435456, 891699423142395494501906828160, 12302820585630191716774996205431296] |