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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 36 |
| 6 | 245 |
| 7 | 2076 |
| 8 | 21059 |
| 9 | 248836 |
| 10 | 3356609 |
| 11 | 50896380 |
| 12 | 856958911 |
| 13 | 15864014388 |
| 14 | 320245960333 |
| 15 | 7001257954796 |
| 16 | 164792092647355 |
| 17 | 4154906594518116 |
| 18 | 111719929072986521 |
| 19 | 3191216673497748444 |
[0,1,1,2,7,36,245,2076,21059,248836,3356609, 50896380,856958911,15864014388,320245960333, 7001257954796,164792092647355,4154906594518116, 111719929072986521,3191216673497748444] |