| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 23 |
| 4 | 176 |
| 5 | 1697 |
| 6 | 19805 |
| 7 | 271669 |
| 8 | 4285195 |
| 9 | 76430799 |
| 10 | 1521161530 |
| 11 | 33422603485 |
| 12 | 803584699252 |
| 13 | 20986514811397 |
| 14 | 591616582807036 |
| 15 | 17905570068475471 |
| 16 | 579092313210791549 |
| 17 | 19931241131544637637 |
| 18 | 727395001560116046739 |
| 19 | 28057672464546863483509 |
| 20 | 1140566596105346550309751 |
| 21 | 48735378037084078566334897 |
| 22 | 2183719157723179429519093520 |
| 23 | 102386962560815561519635957007 |
[1,1,4,23,176,1697,19805,271669,4285195,76430799, 1521161530,33422603485,803584699252, 20986514811397,591616582807036,17905570068475471, 579092313210791549,19931241131544637637, 727395001560116046739,28057672464546863483509, 1140566596105346550309751, 48735378037084078566334897, 2183719157723179429519093520, 102386962560815561519635957007] |