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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 21 |
| 6 | 48 |
| 7 | 146 |
| 8 | 374 |
| 9 | 1041 |
| 10 | 2767 |
| 11 | 7599 |
| 12 | 20335 |
| 13 | 55312 |
| 14 | 148508 |
| 15 | 401587 |
| 16 | 1078120 |
| 17 | 2905750 |
| 18 | 7791872 |
| 19 | 20949044 |
| 20 | 56108088 |
| 21 | 150561505 |
| 22 | 402790471 |
| 23 | 1079193820 |
| 24 | 2884163147 |
| 25 | 7717665942 |
| 26 | 20607086269 |
| 27 | 55082558748 |
| 28 | 146961256062 |
| 29 | 392462843328 |
| 30 | 1046372618275 |
[1,1,3,6,21,48,146,374,1041,2767,7599,20335,55312, 148508,401587,1078120,2905750,7791872,20949044, 56108088,150561505,402790471,1079193820, 2884163147,7717665942,20607086269,55082558748, 146961256062,392462843328,1046372618275] |