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| n | a(n) |
|---|---|
| 5 | 1 |
| 6 | 6 |
| 7 | 20 |
| 8 | 48 |
| 9 | 90 |
| 10 | 132 |
| 11 | 561 |
| 12 | 2420 |
| 13 | 10571 |
| 14 | 46672 |
| 15 | 207963 |
| 16 | 934064 |
| 17 | 4224685 |
| 18 | 19225588 |
| 19 | 87969426 |
| 20 | 404479884 |
| 21 | 1867924322 |
| 22 | 8660317820 |
| 23 | 40295911480 |
| 24 | 188105782260 |
| 25 | 880716750140 |
| 26 | 4134823623820 |
| 27 | 19461238795225 |
| 28 | 91810738725036 |
| 29 | 434062054130187 |
| 30 | 2056265327125528 |
[1,6,20,48,90,132,561,2420,10571,46672,207963, 934064,4224685,19225588,87969426,404479884, 1867924322,8660317820,40295911480,188105782260, 880716750140,4134823623820,19461238795225, 91810738725036,434062054130187,2056265327125528] |