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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 12 |
| 5 | 99 |
| 6 | 688 |
| 7 | 4326 |
| 8 | 25464 |
| 9 | 143018 |
| 10 | 775536 |
| 11 | 4092207 |
| 12 | 21126564 |
| 13 | 107136597 |
| 14 | 535272864 |
| 15 | 2640788828 |
| 16 | 12888228336 |
| 17 | 62312915172 |
| 18 | 298810304672 |
| 19 | 1422537514989 |
| 20 | 6728698090428 |
| 21 | 31643981809111 |
| 22 | 148044975160272 |
| 23 | 689370668876130 |
| 24 | 3196344091219560 |
| 25 | 14762394097629870 |
[0,0,0,1,12,99,688,4326,25464,143018,775536, 4092207,21126564,107136597,535272864,2640788828, 12888228336,62312915172,298810304672, 1422537514989,6728698090428,31643981809111, 148044975160272,689370668876130,3196344091219560, 14762394097629870] |