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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 20 |
| 7 | 102 |
| 8 | 496 |
| 9 | 2294 |
| 10 | 10200 |
| 11 | 44062 |
| 12 | 186416 |
| 13 | 776934 |
| 14 | 3203080 |
| 15 | 13101422 |
| 16 | 53279136 |
| 17 | 215749174 |
| 18 | 870919160 |
| 19 | 3507493182 |
| 20 | 14101520656 |
| 21 | 56620923014 |
| 22 | 227128606440 |
| 23 | 910449955342 |
| 24 | 3647607982976 |
| 25 | 14607859562454 |
| 26 | 58483727432920 |
[1,4,20,102,496,2294,10200,44062,186416,776934, 3203080,13101422,53279136,215749174,870919160, 3507493182,14101520656,56620923014,227128606440, 910449955342,3647607982976,14607859562454, 58483727432920] |