| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 8 |
| 2 | 50 |
| 3 | 344 |
| 4 | 2402 |
| 5 | 16808 |
| 6 | 117650 |
| 7 | 823544 |
| 8 | 5764802 |
| 9 | 40353608 |
| 10 | 282475250 |
| 11 | 1977326744 |
| 12 | 13841287202 |
| 13 | 96889010408 |
| 14 | 678223072850 |
| 15 | 4747561509944 |
| 16 | 33232930569602 |
| 17 | 232630513987208 |
| 18 | 1628413597910450 |
| 19 | 11398895185373144 |
[2,8,50,344,2402,16808,117650,823544,5764802, 40353608,282475250,1977326744,13841287202, 96889010408,678223072850,4747561509944, 33232930569602,232630513987208,1628413597910450, 11398895185373144] |