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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 74 |
| 6 | 253 |
| 7 | 840 |
| 8 | 2728 |
| 9 | 8719 |
| 10 | 27541 |
| 11 | 86221 |
| 12 | 268047 |
| 13 | 828661 |
| 14 | 2550116 |
| 15 | 7818174 |
| 16 | 23893803 |
| 17 | 72831350 |
| 18 | 221504503 |
| 19 | 672394824 |
| 20 | 2037817846 |
| 21 | 6167472211 |
| 22 | 18643839127 |
| 23 | 56301766021 |
| 24 | 169874621301 |
| 25 | 512161584769 |
| 26 | 1543128593438 |
[1,2,6,21,74,253,840,2728,8719,27541,86221,268047, 828661,2550116,7818174,23893803,72831350, 221504503,672394824,2037817846,6167472211, 18643839127,56301766021,169874621301,512161584769, 1543128593438] |