The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 27 |
| 5 | 89 |
| 6 | 272 |
| 7 | 873 |
| 8 | 2859 |
| 9 | 8936 |
| 10 | 25491 |
| 11 | 67665 |
| 12 | 228192 |
| 13 | 752241 |
| 14 | 2167859 |
| 15 | 6833896 |
| 16 | 18464907 |
| 17 | 52758345 |
| 18 | 142005584 |
| 19 | 440498361 |
| 20 | 1186119547 |
| 21 | 3461957320 |
| 22 | 9357060899 |
| 23 | 26968655777 |
| 24 | 72945663424 |
| 25 | 226371206881 |
| 26 | 613739200867 |
| 27 | 1752444795592 |
| 28 | 4702791627067 |
| 29 | 14623717009785 |
[0,1,3,8,27,89,272,873,2859,8936,25491,67665, 228192,752241,2167859,6833896,18464907,52758345, 142005584,440498361,1186119547,3461957320, 9357060899,26968655777,72945663424,226371206881, 613739200867,1752444795592,4702791627067, 14623717009785] |