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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 55 |
| 5 | 199 |
| 6 | 714 |
| 7 | 2548 |
| 8 | 9061 |
| 9 | 32148 |
| 10 | 113887 |
| 11 | 403051 |
| 12 | 1425471 |
| 13 | 5039254 |
| 14 | 17809336 |
| 15 | 62928201 |
| 16 | 222324436 |
| 17 | 785402143 |
| 18 | 2774421135 |
| 19 | 9800231959 |
| 20 | 34617003682 |
| 21 | 122274355596 |
| 22 | 431893332397 |
| 23 | 1525507797700 |
| 24 | 5388281150223 |
[1,4,15,55,199,714,2548,9061,32148,113887,403051, 1425471,5039254,17809336,62928201,222324436, 785402143,2774421135,9800231959,34617003682, 122274355596,431893332397,1525507797700, 5388281150223] |