n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 28 |
3 | 217 |
4 | 1705 |
5 | 13420 |
6 | 105652 |
7 | 831793 |
8 | 6548689 |
9 | 51557716 |
10 | 405913036 |
11 | 3195746569 |
12 | 25160059513 |
13 | 198084729532 |
14 | 1559517776740 |
15 | 12278057484385 |
16 | 96664942098337 |
17 | 761041479302308 |
18 | 5991666892320124 |
19 | 47172293659258681 |
20 | 371386682381749321 |
[1,4,28,217,1705,13420,105652,831793,6548689, 51557716,405913036,3195746569,25160059513, 198084729532,1559517776740,12278057484385, 96664942098337,761041479302308,5991666892320124, 47172293659258681,371386682381749321] |