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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 48 |
| 5 | 186 |
| 6 | 753 |
| 7 | 3097 |
| 8 | 13053 |
| 9 | 55769 |
| 10 | 241140 |
| 11 | 1053164 |
| 12 | 4636881 |
| 13 | 20557358 |
| 14 | 91675021 |
| 15 | 410927024 |
| 16 | 1850129497 |
| 17 | 8362763763 |
| 18 | 37932271619 |
| 19 | 172592759713 |
| 20 | 787505869111 |
| 21 | 3602359497451 |
| 22 | 16516663397884 |
| 23 | 75887948704330 |
| 24 | 349351810417632 |
| 25 | 1611113927635246 |
| 26 | 7442244616664714 |
| 27 | 34430542485823502 |
[1,1,4,13,48,186,753,3097,13053,55769,241140, 1053164,4636881,20557358,91675021,410927024, 1850129497,8362763763,37932271619,172592759713, 787505869111,3602359497451,16516663397884, 75887948704330,349351810417632,1611113927635246, 7442244616664714,34430542485823502] |