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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 96 |
| 6 | 409 |
| 7 | 1751 |
| 8 | 7505 |
| 9 | 32176 |
| 10 | 137956 |
| 11 | 591501 |
| 12 | 2536132 |
| 13 | 10873981 |
| 14 | 46623553 |
| 15 | 199904321 |
| 16 | 857114814 |
| 17 | 3674987126 |
| 18 | 15756967635 |
| 19 | 67559972476 |
| 20 | 289671844661 |
| 21 | 1242004318751 |
| 22 | 5325249092137 |
| 23 | 22832672531956 |
| 24 | 97897943538708 |
[1,1,2,6,23,96,409,1751,7505,32176,137956,591501, 2536132,10873981,46623553,199904321,857114814, 3674987126,15756967635,67559972476,289671844661, 1242004318751,5325249092137,22832672531956, 97897943538708] |