The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 6 |
| 2 | 19 |
| 3 | 59 |
| 4 | 181 |
| 5 | 541 |
| 6 | 1583 |
| 7 | 4455 |
| 8 | 12213 |
| 9 | 32113 |
| 10 | 82631 |
| 11 | 206709 |
| 12 | 510681 |
| 13 | 1245343 |
| 14 | 3004575 |
| 15 | 7200705 |
| 16 | 17049021 |
| 17 | 40140981 |
| 18 | 93678375 |
| 19 | 216274577 |
| 20 | 496470625 |
| 21 | 1128356231 |
| 22 | 2544413119 |
| 23 | 5704402931 |
| 24 | 12712869673 |
| 25 | 28191681427 |
| 26 | 62282778949 |
| 27 | 137195275297 |
| 28 | 300840332783 |
[2,6,19,59,181,541,1583,4455,12213,32113,82631, 206709,510681,1245343,3004575,7200705,17049021, 40140981,93678375,216274577,496470625,1128356231, 2544413119,5704402931,12712869673,28191681427, 62282778949,137195275297,300840332783] |