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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 36 |
| 4 | 217 |
| 5 | 1332 |
| 6 | 8295 |
| 7 | 52221 |
| 8 | 331518 |
| 9 | 2118558 |
| 10 | 13611144 |
| 11 | 87833781 |
| 12 | 568893156 |
| 13 | 3696245515 |
| 14 | 24080248485 |
| 15 | 157245263196 |
| 16 | 1028928699129 |
| 17 | 6744977287656 |
| 18 | 44287036450035 |
| 19 | 291206172153066 |
| 20 | 1917300157617312 |
| 21 | 12638390384014515 |
| 22 | 83398707478813197 |
| 23 | 550874308524107364 |
[1,1,6,36,217,1332,8295,52221,331518,2118558, 13611144,87833781,568893156,3696245515, 24080248485,157245263196,1028928699129, 6744977287656,44287036450035,291206172153066, 1917300157617312,12638390384014515, 83398707478813197,550874308524107364] |