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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 57 |
| 5 | 219 |
| 6 | 923 |
| 7 | 3835 |
| 8 | 16373 |
| 9 | 71049 |
| 10 | 313877 |
| 11 | 1397021 |
| 12 | 6271765 |
| 13 | 28362947 |
| 14 | 129278243 |
| 15 | 592589149 |
| 16 | 2729588805 |
| 17 | 12626351945 |
| 18 | 58652928331 |
| 19 | 273500977443 |
| 20 | 1279554767405 |
| 21 | 6003495416417 |
| 22 | 28243174893659 |
| 23 | 133208726181589 |
| 24 | 629765157737029 |
| 25 | 2983611472578201 |
| 26 | 14162539037245515 |
| 27 | 67348331991380805 |
[1,1,5,15,57,219,923,3835,16373,71049,313877, 1397021,6271765,28362947,129278243,592589149, 2729588805,12626351945,58652928331,273500977443, 1279554767405,6003495416417,28243174893659, 133208726181589,629765157737029,2983611472578201, 14162539037245515,67348331991380805] |