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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 261 |
| 3 | 3393 |
| 4 | 24157 |
| 5 | 129688 |
| 6 | 580609 |
| 7 | 2270671 |
| 8 | 8004754 |
| 9 | 25996789 |
| 10 | 78925762 |
| 11 | 226351177 |
| 12 | 618182705 |
| 13 | 1618088408 |
| 14 | 4079878514 |
| 15 | 9950251364 |
| 16 | 23552795295 |
| 17 | 54265058448 |
| 18 | 121990170516 |
| 19 | 268139111685 |
| 20 | 577310192290 |
| 21 | 1219427979865 |
| 22 | 2530473375487 |
| 23 | 5165077677896 |
[1,0,261,3393,24157,129688,580609,2270671,8004754, 25996789,78925762,226351177,618182705,1618088408, 4079878514,9950251364,23552795295,54265058448, 121990170516,268139111685,577310192290, 1219427979865,2530473375487,5165077677896] |