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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 18 |
| 5 | 58 |
| 6 | 221 |
| 7 | 935 |
| 8 | 4361 |
| 9 | 22082 |
| 10 | 120336 |
| 11 | 700652 |
| 12 | 4333933 |
| 13 | 28345089 |
| 14 | 195233255 |
| 15 | 1411303634 |
| 16 | 10675375402 |
| 17 | 84276173438 |
| 18 | 692752181561 |
| 19 | 5917018378495 |
| 20 | 52416910416933 |
| 21 | 480786834535246 |
| 22 | 4559132648864256 |
| 23 | 44632792689619592 |
| 24 | 450518001943669545 |
[1,1,3,6,18,58,221,935,4361,22082,120336,700652, 4333933,28345089,195233255,1411303634,10675375402, 84276173438,692752181561,5917018378495, 52416910416933,480786834535246,4559132648864256, 44632792689619592,450518001943669545] |