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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 24 |
| 2 | 114 |
| 3 | 426 |
| 4 | 1862 |
| 5 | 8194 |
| 6 | 36996 |
| 7 | 169088 |
| 8 | 781022 |
| 9 | 3635922 |
| 10 | 17034404 |
| 11 | 80221088 |
| 12 | 379426784 |
| 13 | 1801177896 |
| 14 | 8577255542 |
| 15 | 40956427846 |
| 16 | 196033612206 |
| 17 | 940269589202 |
| 18 | 4518417570036 |
| 19 | 21749390784152 |
| 20 | 104848429735272 |
| 21 | 506137481003552 |
[1,24,114,426,1862,8194,36996,169088,781022, 3635922,17034404,80221088,379426784,1801177896, 8577255542,40956427846,196033612206,940269589202, 4518417570036,21749390784152,104848429735272, 506137481003552] |