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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 22 |
| 4 | 88 |
| 5 | 372 |
| 6 | 1632 |
| 7 | 7350 |
| 8 | 33744 |
| 9 | 157188 |
| 10 | 740522 |
| 11 | 3519904 |
| 12 | 16851570 |
| 13 | 81150912 |
| 14 | 392687942 |
| 15 | 1907901166 |
| 16 | 9301268766 |
| 17 | 45476190968 |
| 18 | 222895010996 |
| 19 | 1094818072024 |
| 20 | 5387474604008 |
| 21 | 26553803662396 |
| 22 | 131062764352214 |
| 23 | 647692832232724 |
| 24 | 3204298760223824 |
| 25 | 15867809689100878 |
| 26 | 78645597680434374 |
[1,2,6,22,88,372,1632,7350,33744,157188,740522, 3519904,16851570,81150912,392687942,1907901166, 9301268766,45476190968,222895010996,1094818072024, 5387474604008,26553803662396,131062764352214, 647692832232724,3204298760223824, 15867809689100878,78645597680434374] |