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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 48 |
| 6 | 163 |
| 7 | 573 |
| 8 | 2074 |
| 9 | 7669 |
| 10 | 28860 |
| 11 | 110148 |
| 12 | 425384 |
| 13 | 1659185 |
| 14 | 6526791 |
| 15 | 25863949 |
| 16 | 103151955 |
| 17 | 413728474 |
| 18 | 1667757766 |
| 19 | 6753022725 |
| 20 | 27454555171 |
| 21 | 112024545382 |
| 22 | 458616153319 |
| 23 | 1883201461892 |
| 24 | 7754348091640 |
| 25 | 32010908796160 |
[1,1,2,5,15,48,163,573,2074,7669,28860,110148, 425384,1659185,6526791,25863949,103151955, 413728474,1667757766,6753022725,27454555171, 112024545382,458616153319,1883201461892, 7754348091640,32010908796160] |