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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 23 |
| 6 | 62 |
| 7 | 179 |
| 8 | 549 |
| 9 | 1773 |
| 10 | 6003 |
| 11 | 21233 |
| 12 | 78187 |
| 13 | 298894 |
| 14 | 1183387 |
| 15 | 4842221 |
| 16 | 20438964 |
| 17 | 88849325 |
| 18 | 397183838 |
| 19 | 1823456223 |
| 20 | 8587051052 |
| 21 | 41434641992 |
| 22 | 204654311282 |
| 23 | 1033757421996 |
| 24 | 5335693879201 |
| 25 | 28118977852767 |
| 26 | 151192761513229 |
| 27 | 828884087889407 |
[1,1,2,4,9,23,62,179,549,1773,6003,21233,78187, 298894,1183387,4842221,20438964,88849325, 397183838,1823456223,8587051052,41434641992, 204654311282,1033757421996,5335693879201, 28118977852767,151192761513229,828884087889407] |