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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 32 |
| 6 | 96 |
| 7 | 280 |
| 8 | 840 |
| 9 | 2496 |
| 10 | 7488 |
| 11 | 22400 |
| 12 | 67200 |
| 13 | 201408 |
| 14 | 604224 |
| 15 | 1812112 |
| 16 | 5436336 |
| 17 | 16307328 |
| 18 | 48921984 |
| 19 | 146760960 |
| 20 | 440282880 |
| 21 | 1320833664 |
| 22 | 3962500992 |
| 23 | 11887458176 |
| 24 | 35662374528 |
| 25 | 106986989184 |
| 26 | 320960967552 |
| 27 | 962882499840 |
| 28 | 2888647499520 |
| 29 | 8665941290112 |
[1,2,4,12,32,96,280,840,2496,7488,22400,67200, 201408,604224,1812112,5436336,16307328,48921984, 146760960,440282880,1320833664,3962500992, 11887458176,35662374528,106986989184,320960967552, 962882499840,2888647499520,8665941290112] |