| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 44 |
| 5 | 172 |
| 6 | 684 |
| 7 | 2732 |
| 8 | 10924 |
| 9 | 43692 |
| 10 | 174764 |
| 11 | 699052 |
| 12 | 2796204 |
| 13 | 11184812 |
| 14 | 44739244 |
| 15 | 178956972 |
| 16 | 715827884 |
| 17 | 2863311532 |
| 18 | 11453246124 |
| 19 | 45812984492 |
| 20 | 183251937964 |
| 21 | 733007751852 |
| 22 | 2932031007404 |
| 23 | 11728124029612 |
| 24 | 46912496118444 |
[1,2,4,12,44,172,684,2732,10924,43692,174764, 699052,2796204,11184812,44739244,178956972, 715827884,2863311532,11453246124,45812984492, 183251937964,733007751852,2932031007404, 11728124029612,46912496118444] |