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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 3 |
| 4 | 6 |
| 5 | 10 |
| 6 | 18 |
| 7 | 32 |
| 8 | 80 |
| 9 | 171 |
| 10 | 528 |
| 11 | 1439 |
| 12 | 4889 |
| 13 | 15449 |
| 14 | 53949 |
| 15 | 182180 |
| 16 | 637755 |
| 17 | 2204512 |
| 18 | 7715118 |
| 19 | 26867102 |
| 20 | 93989058 |
| 21 | 328149079 |
| 22 | 1147549260 |
| 23 | 4010085072 |
| 24 | 14021225991 |
| 25 | 49011288024 |
| 26 | 171356237471 |
| 27 | 599040489814 |
| 28 | 2094336965494 |
| 29 | 7321826414980 |
[0,3,3,6,10,18,32,80,171,528,1439,4889,15449, 53949,182180,637755,2204512,7715118,26867102, 93989058,328149079,1147549260,4010085072, 14021225991,49011288024,171356237471,599040489814, 2094336965494,7321826414980] |