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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 34 |
| 6 | 110 |
| 7 | 364 |
| 8 | 1248 |
| 9 | 4356 |
| 10 | 15520 |
| 11 | 56022 |
| 12 | 204726 |
| 13 | 755472 |
| 14 | 2812004 |
| 15 | 10543718 |
| 16 | 39791070 |
| 17 | 151022006 |
| 18 | 576090250 |
| 19 | 2207493080 |
| 20 | 8493196536 |
| 21 | 32797115398 |
| 22 | 127071214442 |
| 23 | 493831241234 |
| 24 | 1924504466246 |
| 25 | 7519182311366 |
| 26 | 29447430754182 |
| 27 | 115577336981932 |
[1,1,2,4,12,34,110,364,1248,4356,15520,56022, 204726,755472,2812004,10543718,39791070,151022006, 576090250,2207493080,8493196536,32797115398, 127071214442,493831241234,1924504466246, 7519182311366,29447430754182,115577336981932] |