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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 19 |
| 4 | 73 |
| 5 | 281 |
| 6 | 1081 |
| 7 | 4159 |
| 8 | 16001 |
| 9 | 61561 |
| 10 | 236845 |
| 11 | 911219 |
| 12 | 3505753 |
| 13 | 13487761 |
| 14 | 51891761 |
| 15 | 199644319 |
| 16 | 768096001 |
| 17 | 2955112721 |
| 18 | 11369270485 |
| 19 | 43741245619 |
| 20 | 168286661033 |
| 21 | 647452990441 |
| 22 | 2490960200041 |
| 23 | 9583526232479 |
| 24 | 36870912288001 |
| 25 | 141854275761481 |
[1,1,5,19,73,281,1081,4159,16001,61561,236845, 911219,3505753,13487761,51891761,199644319, 768096001,2955112721,11369270485,43741245619, 168286661033,647452990441,2490960200041, 9583526232479,36870912288001,141854275761481] |