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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 53 |
| 5 | 162 |
| 6 | 505 |
| 7 | 1548 |
| 8 | 4756 |
| 9 | 14650 |
| 10 | 45065 |
| 11 | 138622 |
| 12 | 426528 |
| 13 | 1312242 |
| 14 | 4037155 |
| 15 | 12420806 |
| 16 | 38213753 |
| 17 | 117567880 |
| 18 | 361708733 |
| 19 | 1112830322 |
| 20 | 3423724282 |
| 21 | 10533403974 |
| 22 | 32406988208 |
| 23 | 99703082744 |
| 24 | 306745721586 |
| 25 | 943731474930 |
[1,2,5,18,53,162,505,1548,4756,14650,45065,138622, 426528,1312242,4037155,12420806,38213753, 117567880,361708733,1112830322,3423724282, 10533403974,32406988208,99703082744,306745721586, 943731474930] |