n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 21 |
4 | 126 |
5 | 818 |
6 | 5594 |
7 | 39693 |
8 | 289510 |
9 | 2157150 |
10 | 16348960 |
11 | 125642146 |
12 | 976789620 |
13 | 7668465964 |
14 | 60708178054 |
15 | 484093913917 |
16 | 3884724864390 |
17 | 31348290348086 |
18 | 254225828706248 |
19 | 2070856216759478 |
20 | 16936016649259364 |
[1,1,4,21,126,818,5594,39693,289510,2157150, 16348960,125642146,976789620,7668465964, 60708178054,484093913917,3884724864390, 31348290348086,254225828706248,2070856216759478, 16936016649259364] |