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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 27 |
| 2 | 377 |
| 3 | 3626 |
| 4 | 26999 |
| 5 | 165852 |
| 6 | 874755 |
| 7 | 4071079 |
| 8 | 17052724 |
| 9 | 65259715 |
| 10 | 230856472 |
| 11 | 761987905 |
| 12 | 2364726003 |
| 13 | 6943746516 |
| 14 | 19395654894 |
| 15 | 51770913911 |
| 16 | 132567002957 |
| 17 | 326758146932 |
| 18 | 777583981286 |
| 19 | 1791153918119 |
| 20 | 4003030425506 |
| 21 | 8697839966552 |
[1,27,377,3626,26999,165852,874755,4071079, 17052724,65259715,230856472,761987905,2364726003, 6943746516,19395654894,51770913911,132567002957, 326758146932,777583981286,1791153918119, 4003030425506,8697839966552] |