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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 61 |
| 5 | 228 |
| 6 | 926 |
| 7 | 4126 |
| 8 | 19688 |
| 9 | 101582 |
| 10 | 556763 |
| 11 | 3258810 |
| 12 | 20134527 |
| 13 | 131591030 |
| 14 | 902915694 |
| 15 | 6506096000 |
| 16 | 48986713992 |
| 17 | 385159376478 |
| 18 | 3151457714098 |
| 19 | 26806601933838 |
| 20 | 236457090358459 |
| 21 | 2160451562170100 |
| 22 | 20408176433186475 |
| 23 | 199086685731569740 |
| 24 | 2002713693735431017 |
[1,2,6,18,61,228,926,4126,19688,101582,556763, 3258810,20134527,131591030,902915694,6506096000, 48986713992,385159376478,3151457714098, 26806601933838,236457090358459,2160451562170100, 20408176433186475,199086685731569740, 2002713693735431017] |