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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 71 |
| 5 | 243 |
| 6 | 1173 |
| 7 | 4425 |
| 8 | 21623 |
| 9 | 85595 |
| 10 | 420601 |
| 11 | 1718067 |
| 12 | 8475957 |
| 13 | 35414065 |
| 14 | 175191261 |
| 15 | 744299953 |
| 16 | 3688985463 |
| 17 | 15875795231 |
| 18 | 78795932287 |
| 19 | 342608596111 |
| 20 | 1702289233577 |
| 21 | 7464047307389 |
| 22 | 37117102285215 |
| 23 | 163889023336193 |
| 24 | 815531984477949 |
| 25 | 3622301825830109 |
| 26 | 18034891620843507 |
| 27 | 80511836008740271 |
[1,1,5,15,71,243,1173,4425,21623,85595,420601, 1718067,8475957,35414065,175191261,744299953, 3688985463,15875795231,78795932287,342608596111, 1702289233577,7464047307389,37117102285215, 163889023336193,815531984477949,3622301825830109, 18034891620843507,80511836008740271] |