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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 10 |
| 6 | 20 |
| 7 | 40 |
| 8 | 80 |
| 9 | 150 |
| 10 | 280 |
| 11 | 522 |
| 12 | 965 |
| 13 | 1802 |
| 14 | 3393 |
| 15 | 6426 |
| 16 | 12197 |
| 17 | 23236 |
| 18 | 44419 |
| 19 | 85116 |
| 20 | 163543 |
| 21 | 314837 |
| 22 | 607440 |
| 23 | 1174134 |
| 24 | 2273619 |
| 25 | 4409116 |
| 26 | 8561931 |
| 27 | 16646790 |
| 28 | 32404446 |
| 29 | 63145533 |
| 30 | 123173667 |
[0,0,1,2,5,10,20,40,80,150,280,522,965,1802,3393, 6426,12197,23236,44419,85116,163543,314837,607440, 1174134,2273619,4409116,8561931,16646790,32404446, 63145533,123173667] |