The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 8 |
| 5 | 14 |
| 6 | 40 |
| 7 | 86 |
| 8 | 222 |
| 9 | 518 |
| 10 | 1296 |
| 11 | 3130 |
| 12 | 7770 |
| 13 | 19066 |
| 14 | 47324 |
| 15 | 117094 |
| 16 | 291260 |
| 17 | 724302 |
| 18 | 1806220 |
| 19 | 4507230 |
| 20 | 11266718 |
| 21 | 28188070 |
| 22 | 70609316 |
| 23 | 177023466 |
| 24 | 444231564 |
| 25 | 1115639586 |
| 26 | 2803975860 |
| 27 | 7052132546 |
| 28 | 17748069294 |
| 29 | 44693162266 |
[1,0,2,2,8,14,40,86,222,518,1296,3130,7770,19066, 47324,117094,291260,724302,1806220,4507230, 11266718,28188070,70609316,177023466,444231564, 1115639586,2803975860,7052132546,17748069294, 44693162266] |