n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 20 |
4 | 124 |
5 | 932 |
6 | 8284 |
7 | 85220 |
8 | 997084 |
9 | 13082852 |
10 | 190320604 |
11 | 3040770020 |
12 | 52937870044 |
13 | 997533561572 |
14 | 20228969244124 |
15 | 439283696014820 |
16 | 10170742982007004 |
17 | 250110224694309092 |
18 | 6510327792455418844 |
19 | 178832105312143131620 |
20 | 5169772417850111583964 |
[1,1,4,20,124,932,8284,85220,997084,13082852, 190320604,3040770020,52937870044,997533561572, 20228969244124,439283696014820,10170742982007004, 250110224694309092,6510327792455418844, 178832105312143131620,5169772417850111583964] |