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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 64 |
| 6 | 219 |
| 7 | 777 |
| 8 | 2803 |
| 9 | 10315 |
| 10 | 38496 |
| 11 | 145516 |
| 12 | 555764 |
| 13 | 2142060 |
| 14 | 8320207 |
| 15 | 32538518 |
| 16 | 128012533 |
| 17 | 506300507 |
| 18 | 2011932479 |
| 19 | 8028941336 |
| 20 | 32163411045 |
| 21 | 129291553211 |
| 22 | 521372223648 |
| 23 | 2108522273338 |
| 24 | 8549844313915 |
| 25 | 34753397386201 |
| 26 | 141584261960345 |
[1,1,2,6,19,64,219,777,2803,10315,38496,145516, 555764,2142060,8320207,32538518,128012533, 506300507,2011932479,8028941336,32163411045, 129291553211,521372223648,2108522273338, 8549844313915,34753397386201,141584261960345] |