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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 20 |
| 4 | 66 |
| 5 | 342 |
| 6 | 34092 |
| 7 | 40842 |
| 8 | 41922 |
| 9 | 46242 |
| 10 | 55422 |
| 11 | 207624 |
| 12 | 259448 |
| 13 | 533172 |
| 14 | 547300 |
| 15 | 571992 |
| 16 | 667408 |
| 17 | 1531032 |
| 18 | 1786288 |
| 19 | 10983114 |
| 20 | 114013752 |
| 21 | 133506680 |
| 22 | 323277822 |
| 23 | 347360860 |
| 24 | 386144360 |
| 25 | 387415458 |
| 26 | 459603716 |
| 27 | 476991704 |
| 28 | 1443279992 |
| 29 | 1539484232 |
| 30 | 15537978552 |
[2,4,20,66,342,34092,40842,41922,46242,55422, 207624,259448,533172,547300,571992,667408,1531032, 1786288,10983114,114013752,133506680,323277822, 347360860,386144360,387415458,459603716,476991704, 1443279992,1539484232,15537978552] |