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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 25 |
| 4 | 99 |
| 5 | 407 |
| 6 | 1736 |
| 7 | 7584 |
| 8 | 33771 |
| 9 | 152633 |
| 10 | 697966 |
| 11 | 3222902 |
| 12 | 15000588 |
| 13 | 70287630 |
| 14 | 331218105 |
| 15 | 1568416959 |
| 16 | 7458237045 |
| 17 | 35596100785 |
| 18 | 170438383971 |
| 19 | 818403513883 |
| 20 | 3939723976715 |
| 21 | 19008401989542 |
| 22 | 91898156436871 |
| 23 | 445105730900628 |
| 24 | 2159434063875192 |
| 25 | 10492328046710094 |
| 26 | 51050700215626557 |
| 27 | 248701904388999187 |
[1,2,7,25,99,407,1736,7584,33771,152633,697966, 3222902,15000588,70287630,331218105,1568416959, 7458237045,35596100785,170438383971,818403513883, 3939723976715,19008401989542,91898156436871, 445105730900628,2159434063875192, 10492328046710094,51050700215626557, 248701904388999187] |