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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 46 |
| 3 | 652 |
| 4 | 10186 |
| 5 | 168304 |
| 6 | 2884456 |
| 7 | 50723824 |
| 8 | 909192538 |
| 9 | 16538659384 |
| 10 | 304391739796 |
| 11 | 5655971294824 |
| 12 | 105929883322576 |
| 13 | 1997228410630912 |
| 14 | 37871584674309376 |
| 15 | 721672204654077952 |
| 16 | 13811327854028171098 |
| 17 | 265324110145941691912 |
| 18 | 5114208160758838538044 |
| 19 | 98874597697991698311832 |
| 20 | 1916741738060370782929036 |
[1,4,46,652,10186,168304,2884456,50723824, 909192538,16538659384,304391739796,5655971294824, 105929883322576,1997228410630912, 37871584674309376,721672204654077952, 13811327854028171098,265324110145941691912, 5114208160758838538044,98874597697991698311832, 1916741738060370782929036] |