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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 73 |
| 4 | 369 |
| 5 | 1959 |
| 6 | 10912 |
| 7 | 63543 |
| 8 | 385341 |
| 9 | 2424988 |
| 10 | 15788469 |
| 11 | 106075089 |
| 12 | 733801709 |
| 13 | 5217101283 |
| 14 | 38060759175 |
| 15 | 284533309380 |
| 16 | 2177136417042 |
| 17 | 17032924895739 |
| 18 | 136129119703837 |
| 19 | 1110507731328900 |
| 20 | 9240322072954209 |
[1,3,15,73,369,1959,10912,63543,385341,2424988, 15788469,106075089,733801709,5217101283, 38060759175,284533309380,2177136417042, 17032924895739,136129119703837,1110507731328900, 9240322072954209] |