The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 5 |
| 2 | 13 |
| 3 | 40 |
| 4 | 121 |
| 5 | 365 |
| 6 | 1094 |
| 7 | 3281 |
| 8 | 9841 |
| 9 | 29524 |
| 10 | 88573 |
| 11 | 265721 |
| 12 | 797162 |
| 13 | 2391485 |
| 14 | 7174453 |
| 15 | 21523360 |
| 16 | 64570081 |
| 17 | 193710245 |
| 18 | 581130734 |
| 19 | 1743392201 |
| 20 | 5230176601 |
| 21 | 15690529804 |
| 22 | 47071589413 |
| 23 | 141214768241 |
| 24 | 423644304722 |
| 25 | 1270932914165 |
| 26 | 3812798742493 |
| 27 | 11438396227480 |
[2,5,13,40,121,365,1094,3281,9841,29524,88573, 265721,797162,2391485,7174453,21523360,64570081, 193710245,581130734,1743392201,5230176601, 15690529804,47071589413,141214768241,423644304722, 1270932914165,3812798742493,11438396227480] |