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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 27 |
| 5 | 90 |
| 6 | 330 |
| 7 | 1225 |
| 8 | 4729 |
| 9 | 18554 |
| 10 | 74234 |
| 11 | 300828 |
| 12 | 1233992 |
| 13 | 5110067 |
| 14 | 21341337 |
| 15 | 89768701 |
| 16 | 379995230 |
| 17 | 1617476520 |
| 18 | 6918987187 |
| 19 | 29727655820 |
| 20 | 128233521698 |
| 21 | 555136090343 |
| 22 | 2411084930425 |
| 23 | 10503086930643 |
| 24 | 45878043207696 |
| 25 | 200900611229570 |
| 26 | 881783809570251 |
[1,3,8,27,90,330,1225,4729,18554,74234,300828, 1233992,5110067,21341337,89768701,379995230, 1617476520,6918987187,29727655820,128233521698, 555136090343,2411084930425,10503086930643, 45878043207696,200900611229570,881783809570251] |