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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 14 |
| 4 | 41 |
| 5 | 143 |
| 6 | 472 |
| 7 | 1562 |
| 8 | 5233 |
| 9 | 17395 |
| 10 | 58002 |
| 11 | 193346 |
| 12 | 644219 |
| 13 | 2147421 |
| 14 | 7156704 |
| 15 | 23852324 |
| 16 | 79497767 |
| 17 | 264952955 |
| 18 | 883057354 |
| 19 | 2943113598 |
| 20 | 9809007073 |
| 21 | 32692164351 |
| 22 | 108958689984 |
| 23 | 363145140266 |
| 24 | 1210315480391 |
| 25 | 4033823637937 |
| 26 | 13444208923518 |
| 27 | 44807796457932 |
[1,1,4,14,41,143,472,1562,5233,17395,58002,193346, 644219,2147421,7156704,23852324,79497767, 264952955,883057354,2943113598,9809007073, 32692164351,108958689984,363145140266, 1210315480391,4033823637937,13444208923518, 44807796457932] |