The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 28 |
| 4 | 56 |
| 5 | 60 |
| 6 | 84 |
| 7 | 160 |
| 8 | 168 |
| 9 | 528 |
| 10 | 12936 |
| 11 | 32760 |
| 12 | 102960 |
| 13 | 1097280 |
| 14 | 1778400 |
| 15 | 11740302 |
| 16 | 19183500 |
| 17 | 25241600 |
| 18 | 235855620 |
| 19 | 308308000 |
| 20 | 317167200 |
| 21 | 424305000 |
| 22 | 459818240 |
| 23 | 704700000 |
| 24 | 787200000 |
| 25 | 924924000 |
| 26 | 1592025435 |
| 27 | 2701416960 |
| 28 | 3812244480 |
[1,2,28,56,60,84,160,168,528,12936,32760,102960, 1097280,1778400,11740302,19183500,25241600, 235855620,308308000,317167200,424305000,459818240, 704700000,787200000,924924000,1592025435, 2701416960,3812244480] |