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| n | a(n) |
|---|---|
| 1 | 12 |
| 2 | 144 |
| 3 | 636 |
| 4 | 2709 |
| 5 | 13132 |
| 6 | 54684 |
| 7 | 210118 |
| 8 | 818892 |
| 9 | 3093184 |
| 10 | 11234900 |
| 11 | 40417797 |
| 12 | 143649720 |
| 13 | 501215991 |
| 14 | 1730494710 |
| 15 | 5926924410 |
| 16 | 20097642000 |
| 17 | 67608559928 |
| 18 | 226048464005 |
| 19 | 751020224850 |
| 20 | 2480966742240 |
| 21 | 8157248135323 |
| 22 | 26701216937370 |
[12,144,636,2709,13132,54684,210118,818892, 3093184,11234900,40417797,143649720,501215991, 1730494710,5926924410,20097642000,67608559928, 226048464005,751020224850,2480966742240, 8157248135323,26701216937370] |