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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 10 |
| 3 | 30 |
| 4 | 101 |
| 5 | 361 |
| 6 | 1354 |
| 7 | 5238 |
| 8 | 20740 |
| 9 | 83683 |
| 10 | 342719 |
| 11 | 1421019 |
| 12 | 5953306 |
| 13 | 25162342 |
| 14 | 107163924 |
| 15 | 459438524 |
| 16 | 1981247950 |
| 17 | 8588054014 |
| 18 | 37398421941 |
| 19 | 163534601567 |
| 20 | 717776072291 |
| 21 | 3161117717887 |
| 22 | 13964782042188 |
| 23 | 61866495037806 |
| 24 | 274792382789958 |
[1,4,10,30,101,361,1354,5238,20740,83683,342719, 1421019,5953306,25162342,107163924,459438524, 1981247950,8588054014,37398421941,163534601567, 717776072291,3161117717887,13964782042188, 61866495037806,274792382789958] |