n | a(n) |
---|---|
1 | 4 |
2 | 20 |
3 | 68 |
4 | 308 |
5 | 1320 |
6 | 5220 |
7 | 22652 |
8 | 95220 |
9 | 390580 |
10 | 1662564 |
11 | 6961252 |
12 | 28957492 |
13 | 122178532 |
14 | 511463444 |
15 | 2138409476 |
16 | 8987766644 |
17 | 37641997156 |
18 | 157656704660 |
19 | 661559870852 |
20 | 2771791087028 |
21 | 11615849382436 |
22 | 48710299475156 |
[4,20,68,308,1320,5220,22652,95220,390580,1662564, 6961252,28957492,122178532,511463444,2138409476, 8987766644,37641997156,157656704660,661559870852, 2771791087028,11615849382436,48710299475156] |