The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |
| 4 | 50 |
| 5 | 98 |
| 6 | 242 |
| 7 | 450 |
| 8 | 1058 |
| 9 | 1922 |
| 10 | 4418 |
| 11 | 7938 |
| 12 | 18050 |
| 13 | 32258 |
| 14 | 72962 |
| 15 | 130050 |
| 16 | 293378 |
| 17 | 522242 |
| 18 | 1176578 |
| 19 | 2093058 |
| 20 | 4712450 |
| 21 | 8380418 |
| 22 | 18862082 |
| 23 | 33538050 |
| 24 | 75472898 |
| 25 | 134184962 |
| 26 | 301940738 |
| 27 | 536805378 |
| 28 | 1207861250 |
| 29 | 2147352578 |
| 30 | 4831641602 |
[2,8,18,50,98,242,450,1058,1922,4418,7938,18050, 32258,72962,130050,293378,522242,1176578,2093058, 4712450,8380418,18862082,33538050,75472898, 134184962,301940738,536805378,1207861250, 2147352578,4831641602] |