n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 21 |
3 | 148 |
4 | 980 |
5 | 6444 |
6 | 41888 |
7 | 270088 |
8 | 1730079 |
9 | 11023480 |
10 | 69930146 |
11 | 441988260 |
12 | 2784820519 |
13 | 17499028820 |
14 | 109701885600 |
15 | 686313858480 |
16 | 4285914086100 |
17 | 26721615383496 |
18 | 166361793070466 |
19 | 1034375862301240 |
20 | 6423778211164860 |
21 | 39850734775066644 |
22 | 246976735839649218 |
[1,4,21,148,980,6444,41888,270088,1730079, 11023480,69930146,441988260,2784820519, 17499028820,109701885600,686313858480, 4285914086100,26721615383496,166361793070466, 1034375862301240,6423778211164860, 39850734775066644,246976735839649218] |