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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 4 |
| 3 | 3 |
| 4 | 24 |
| 5 | 60 |
| 6 | 93 |
| 7 | 297 |
| 8 | 507 |
| 9 | 1264 |
| 10 | 2850 |
| 11 | 6180 |
| 12 | 15453 |
| 13 | 33463 |
| 14 | 81394 |
| 15 | 185671 |
| 16 | 428769 |
| 17 | 1005669 |
| 18 | 2301449 |
| 19 | 5384371 |
| 20 | 12403537 |
| 21 | 28828484 |
| 22 | 66828140 |
| 23 | 154614938 |
| 24 | 359224400 |
| 25 | 831157978 |
| 26 | 1928175521 |
| 27 | 4468984943 |
| 28 | 10355201708 |
| 29 | 24011010277 |
| 30 | 55638167866 |
[4,4,3,24,60,93,297,507,1264,2850,6180,15453, 33463,81394,185671,428769,1005669,2301449,5384371, 12403537,28828484,66828140,154614938,359224400, 831157978,1928175521,4468984943,10355201708, 24011010277,55638167866] |