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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 22 |
| 4 | 92 |
| 5 | 424 |
| 6 | 2108 |
| 7 | 11134 |
| 8 | 61748 |
| 9 | 356296 |
| 10 | 2123720 |
| 11 | 13002840 |
| 12 | 81417520 |
| 13 | 519550880 |
| 14 | 3369559864 |
| 15 | 22161337742 |
| 16 | 147544048324 |
| 17 | 992923683912 |
| 18 | 6746101933304 |
| 19 | 46226667046360 |
| 20 | 319199694771696 |
| 21 | 2219445498261152 |
| 22 | 15529758665102416 |
| 23 | 109291258152550712 |
[1,2,6,22,92,424,2108,11134,61748,356296,2123720, 13002840,81417520,519550880,3369559864, 22161337742,147544048324,992923683912, 6746101933304,46226667046360,319199694771696, 2219445498261152,15529758665102416, 109291258152550712] |