n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 15 |
3 | 57 |
4 | 216 |
5 | 819 |
6 | 3105 |
7 | 11772 |
8 | 44631 |
9 | 169209 |
10 | 641520 |
11 | 2432187 |
12 | 9221121 |
13 | 34959924 |
14 | 132543135 |
15 | 502509177 |
16 | 1905156936 |
17 | 7222998339 |
18 | 27384465825 |
19 | 103822392492 |
20 | 393620574951 |
21 | 1492328902329 |
22 | 5657848431840 |
23 | 21450532002507 |
[1,4,15,57,216,819,3105,11772,44631,169209,641520, 2432187,9221121,34959924,132543135,502509177, 1905156936,7222998339,27384465825,103822392492, 393620574951,1492328902329,5657848431840, 21450532002507] |