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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 67 |
| 5 | 411 |
| 6 | 2911 |
| 7 | 23563 |
| 8 | 213543 |
| 9 | 2149927 |
| 10 | 23759791 |
| 11 | 286370151 |
| 12 | 3734929903 |
| 13 | 52455166063 |
| 14 | 788704078527 |
| 15 | 12648867695311 |
| 16 | 215433088624351 |
| 17 | 3884791172487903 |
| 18 | 73919882720901823 |
| 19 | 1480542628345939807 |
| 20 | 31128584449987511871 |
| 21 | 685635398619169059391 |
[1,3,13,67,411,2911,23563,213543,2149927,23759791, 286370151,3734929903,52455166063,788704078527, 12648867695311,215433088624351,3884791172487903, 73919882720901823,1480542628345939807, 31128584449987511871,685635398619169059391] |