The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 26 |
| 2 | 390 |
| 3 | 4420 |
| 4 | 41990 |
| 5 | 352716 |
| 6 | 2704156 |
| 7 | 19315400 |
| 8 | 130378950 |
| 9 | 840219900 |
| 10 | 5209363380 |
| 11 | 31256180280 |
| 12 | 182327718300 |
| 13 | 1037865473400 |
| 14 | 5782393351800 |
| 15 | 31610416989840 |
| 16 | 169905991320390 |
| 17 | 899502306990300 |
| 18 | 4697400936504900 |
| 19 | 24228699567235800 |
| 20 | 123566367792902580 |
| 21 | 623715951716555880 |
[1,26,390,4420,41990,352716,2704156,19315400, 130378950,840219900,5209363380,31256180280, 182327718300,1037865473400,5782393351800, 31610416989840,169905991320390,899502306990300, 4697400936504900,24228699567235800, 123566367792902580,623715951716555880] |