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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 30 |
| 3 | 1156 |
| 4 | 7612 |
| 5 | 66294 |
| 6 | 276762 |
| 7 | 1231304 |
| 8 | 3780600 |
| 9 | 11549290 |
| 10 | 28599190 |
| 11 | 69230412 |
| 12 | 147079860 |
| 13 | 304811486 |
| 14 | 578865042 |
| 15 | 1074611344 |
| 16 | 1875204592 |
| 17 | 3208049874 |
| 18 | 5242291470 |
| 19 | 8421730580 |
| 20 | 13061681580 |
| 21 | 19963508422 |
| 22 | 29676180490 |
| 23 | 43560086616 |
[2,30,1156,7612,66294,276762,1231304,3780600, 11549290,28599190,69230412,147079860,304811486, 578865042,1074611344,1875204592,3208049874, 5242291470,8421730580,13061681580,19963508422, 29676180490,43560086616] |