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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 26 |
| 4 | 118 |
| 5 | 572 |
| 6 | 3127 |
| 7 | 18146 |
| 8 | 114793 |
| 9 | 765602 |
| 10 | 5463982 |
| 11 | 40870436 |
| 12 | 323326813 |
| 13 | 2667777842 |
| 14 | 23092966267 |
| 15 | 207651618746 |
| 16 | 1947316349278 |
| 17 | 18906249136892 |
| 18 | 190564801592107 |
| 19 | 1982986181092226 |
| 20 | 21345005629846213 |
| 21 | 236628248493001202 |
[1,2,7,26,118,572,3127,18146,114793,765602, 5463982,40870436,323326813,2667777842,23092966267, 207651618746,1947316349278,18906249136892, 190564801592107,1982986181092226, 21345005629846213,236628248493001202] |