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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 23 |
| 6 | 48 |
| 7 | 105 |
| 8 | 228 |
| 9 | 486 |
| 10 | 1026 |
| 11 | 2161 |
| 12 | 4548 |
| 13 | 9555 |
| 14 | 20026 |
| 15 | 41874 |
| 16 | 87384 |
| 17 | 182043 |
| 18 | 378648 |
| 19 | 786429 |
| 20 | 1631120 |
| 21 | 3378750 |
| 22 | 6990510 |
| 23 | 14447045 |
| 24 | 29826156 |
| 25 | 61516455 |
| 26 | 126761190 |
| 27 | 260978922 |
| 28 | 536870916 |
| 29 | 1103567983 |
| 30 | 2266788288 |
| 31 | 4652881233 |
| 32 | 9544371772 |
| 33 | 19565962134 |
[0,0,2,6,12,23,48,105,228,486,1026,2161,4548,9555, 20026,41874,87384,182043,378648,786429,1631120, 3378750,6990510,14447045,29826156,61516455, 126761190,260978922,536870916,1103567983, 2266788288,4652881233,9544371772,19565962134] |