| n | a(n) |
|---|---|
| 2 | 54 |
| 3 | 1140 |
| 4 | 26550 |
| 5 | 605556 |
| 6 | 14330736 |
| 7 | 340860960 |
| 8 | 8264889270 |
| 9 | 201651836100 |
| 10 | 4978317147804 |
| 11 | 123546256876224 |
| 12 | 3090501687886704 |
| 13 | 77632745316063840 |
| 14 | 1961313438507566400 |
| 15 | 49717549985405892480 |
| 16 | 1265749551338006549430 |
| 17 | 32312920048897640674500 |
| 18 | 827693426702217868006500 |
[54,1140,26550,605556,14330736,340860960, 8264889270,201651836100,4978317147804, 123546256876224,3090501687886704, 77632745316063840,1961313438507566400, 49717549985405892480,1265749551338006549430, 32312920048897640674500,827693426702217868006500] |