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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 70 |
| 5 | 262 |
| 6 | 1032 |
| 7 | 4112 |
| 8 | 16957 |
| 9 | 70398 |
| 10 | 298251 |
| 11 | 1270136 |
| 12 | 5487853 |
| 13 | 23805317 |
| 14 | 104335318 |
| 15 | 458787703 |
| 16 | 2033142273 |
| 17 | 9034828874 |
| 18 | 40391226251 |
| 19 | 181002360289 |
| 20 | 814984158174 |
| 21 | 3677166565567 |
| 22 | 16655289870081 |
| 23 | 75576045748501 |
| 24 | 344027018703874 |
| 25 | 1568580172677172 |
| 26 | 7170851368252416 |
| 27 | 32829693164473705 |
[1,2,6,19,70,262,1032,4112,16957,70398,298251, 1270136,5487853,23805317,104335318,458787703, 2033142273,9034828874,40391226251,181002360289, 814984158174,3677166565567,16655289870081, 75576045748501,344027018703874,1568580172677172, 7170851368252416,32829693164473705] |