# A118069 (b-file synthesized from sequence entry)
0 4
1 4
2 9
3 25
4 25
5 121
6 721
7 5041
8 40321
9 362881
10 3628801
11 39916813
12 479001601
13 6227020801
14 87178291201
15 1307674368001
16 20922789888001
17 355687428096001
18 6402373705728001
19 121645100408832001
20 2432902008176640001