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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 98 |
| 6 | 434 |
| 7 | 1949 |
| 8 | 8803 |
| 9 | 39888 |
| 10 | 181201 |
| 11 | 825201 |
| 12 | 3767757 |
| 13 | 17249560 |
| 14 | 79191480 |
| 15 | 364585230 |
| 16 | 1683208515 |
| 17 | 7792546040 |
| 18 | 36174065285 |
| 19 | 168367375735 |
| 20 | 785637327745 |
| 21 | 3674914227120 |
| 22 | 17230132657815 |
| 23 | 80965662243526 |
| 24 | 381275131584373 |
| 25 | 1799105397745998 |
[1,1,2,6,23,98,434,1949,8803,39888,181201,825201, 3767757,17249560,79191480,364585230,1683208515, 7792546040,36174065285,168367375735,785637327745, 3674914227120,17230132657815,80965662243526, 381275131584373,1799105397745998] |