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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 16 |
| 4 | 52 |
| 5 | 160 |
| 6 | 9232 |
| 7 | 27700 |
| 8 | 83104 |
| 9 | 599056 |
| 10 | 1797172 |
| 11 | 5391520 |
| 12 | 38862808 |
| 13 | 131161984 |
| 14 | 393485956 |
| 15 | 1180457872 |
| 16 | 3541373620 |
| 17 | 10624120864 |
| 18 | 87327950740 |
| 19 | 261983852224 |
| 20 | 785951556676 |
| 21 | 2357854670032 |
| 22 | 7553654536192 |
| 23 | 22660963608580 |
| 24 | 67982890825744 |
| 25 | 203948672477236 |
[1,2,16,52,160,9232,27700,83104,599056,1797172, 5391520,38862808,131161984,393485956,1180457872, 3541373620,10624120864,87327950740,261983852224, 785951556676,2357854670032,7553654536192, 22660963608580,67982890825744,203948672477236] |