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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 4 |
| 4 | 18 |
| 5 | 71 |
| 6 | 126 |
| 7 | 225 |
| 8 | 691 |
| 9 | 2116 |
| 10 | 6101 |
| 11 | 15907 |
| 12 | 40782 |
| 13 | 110244 |
| 14 | 304223 |
| 15 | 831408 |
| 16 | 2242597 |
| 17 | 6029313 |
| 18 | 16289354 |
| 19 | 44168735 |
| 20 | 119711796 |
| 21 | 323891119 |
| 22 | 875720673 |
| 23 | 2368763705 |
| 24 | 6410688069 |
| 25 | 17350642443 |
| 26 | 46950362332 |
| 27 | 127030237584 |
| 28 | 343705347091 |
[1,3,4,18,71,126,225,691,2116,6101,15907,40782, 110244,304223,831408,2242597,6029313,16289354, 44168735,119711796,323891119,875720673,2368763705, 6410688069,17350642443,46950362332,127030237584, 343705347091] |