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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 59 |
| 6 | 258 |
| 7 | 1296 |
| 8 | 7362 |
| 9 | 46609 |
| 10 | 325147 |
| 11 | 2477212 |
| 12 | 20460278 |
| 13 | 182076531 |
| 14 | 1736623109 |
| 15 | 17672266151 |
| 16 | 191111489038 |
| 17 | 2188592796698 |
| 18 | 26458831601847 |
| 19 | 336735773968857 |
| 20 | 4500142285227330 |
| 21 | 63007188219787855 |
| 22 | 922312862937555109 |
[0,1,2,5,16,59,258,1296,7362,46609,325147,2477212, 20460278,182076531,1736623109,17672266151, 191111489038,2188592796698,26458831601847, 336735773968857,4500142285227330, 63007188219787855,922312862937555109] |