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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 14 |
| 7 | 44 |
| 8 | 133 |
| 9 | 388 |
| 10 | 1116 |
| 11 | 3168 |
| 12 | 8938 |
| 13 | 25100 |
| 14 | 70334 |
| 15 | 196824 |
| 16 | 550656 |
| 17 | 1540832 |
| 18 | 4314190 |
| 19 | 12089368 |
| 20 | 33911543 |
| 21 | 95228760 |
| 22 | 267727154 |
| 23 | 753579420 |
| 24 | 2123637318 |
| 25 | 5991571428 |
| 26 | 16923929406 |
| 27 | 47857425416 |
| 28 | 135478757308 |
| 29 | 383929643780 |
| 30 | 1089118243128 |
| 31 | 3092612497260 |
[1,4,14,44,133,388,1116,3168,8938,25100,70334, 196824,550656,1540832,4314190,12089368,33911543, 95228760,267727154,753579420,2123637318, 5991571428,16923929406,47857425416,135478757308, 383929643780,1089118243128,3092612497260] |