| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 4 |
| 2 | 72 |
| 3 | 1292 |
| 4 | 23184 |
| 5 | 416020 |
| 6 | 7465176 |
| 7 | 133957148 |
| 8 | 2403763488 |
| 9 | 43133785636 |
| 10 | 774004377960 |
| 11 | 13888945017644 |
| 12 | 249227005939632 |
| 13 | 4472197161895732 |
| 14 | 80250321908183544 |
| 15 | 1440033597185408060 |
| 16 | 25840354427429161536 |
[0,4,72,1292,23184,416020,7465176,133957148, 2403763488,43133785636,774004377960, 13888945017644,249227005939632,4472197161895732, 80250321908183544,1440033597185408060, 25840354427429161536] |