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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 16 |
| 6 | 38 |
| 7 | 97 |
| 8 | 262 |
| 9 | 758 |
| 10 | 2298 |
| 11 | 7258 |
| 12 | 23648 |
| 13 | 79056 |
| 14 | 269628 |
| 15 | 935327 |
| 16 | 3290259 |
| 17 | 11714284 |
| 18 | 42139052 |
| 19 | 152963036 |
| 20 | 559697096 |
| 21 | 2062573999 |
| 22 | 7649550571 |
| 23 | 28534096987 |
| 24 | 106994891145 |
| 25 | 403119433265 |
| 26 | 1525466082178 |
| 27 | 5795853930651 |
| 28 | 22102635416715 |
| 29 | 84579153865569 |
[1,0,1,3,7,16,38,97,262,758,2298,7258,23648,79056, 269628,935327,3290259,11714284,42139052,152963036, 559697096,2062573999,7649550571,28534096987, 106994891145,403119433265,1525466082178, 5795853930651,22102635416715,84579153865569] |