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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 33 |
| 4 | 173 |
| 5 | 962 |
| 6 | 5589 |
| 7 | 33546 |
| 8 | 206359 |
| 9 | 1294096 |
| 10 | 8242375 |
| 11 | 53173095 |
| 12 | 346724250 |
| 13 | 2281555440 |
| 14 | 15131448440 |
| 15 | 101038950441 |
| 16 | 678724811604 |
| 17 | 4583483218340 |
| 18 | 31098830566098 |
| 19 | 211898222878937 |
| 20 | 1449322361547669 |
| 21 | 9947227335902244 |
| 22 | 68486384818253877 |
[1,2,7,33,173,962,5589,33546,206359,1294096, 8242375,53173095,346724250,2281555440,15131448440, 101038950441,678724811604,4583483218340, 31098830566098,211898222878937,1449322361547669, 9947227335902244,68486384818253877] |