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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 8 |
| 5 | 22 |
| 6 | 54 |
| 7 | 142 |
| 8 | 370 |
| 9 | 983 |
| 10 | 2627 |
| 11 | 7086 |
| 12 | 19238 |
| 13 | 52561 |
| 14 | 144377 |
| 15 | 398518 |
| 16 | 1104794 |
| 17 | 3074809 |
| 18 | 8588093 |
| 19 | 24064642 |
| 20 | 67630898 |
| 21 | 190584766 |
| 22 | 538412426 |
| 23 | 1524554956 |
| 24 | 4326119748 |
| 25 | 12300296227 |
| 26 | 35037658099 |
| 27 | 99977847308 |
| 28 | 285741659312 |
| 29 | 817901027070 |
| 30 | 2344475178110 |
[0,1,1,4,8,22,54,142,370,983,2627,7086,19238, 52561,144377,398518,1104794,3074809,8588093, 24064642,67630898,190584766,538412426,1524554956, 4326119748,12300296227,35037658099,99977847308, 285741659312,817901027070,2344475178110] |