# A001257 (b-file synthesized from sequence entry)
0 1
1 1
2 4
3 16
4 81
5 400
6 2304
7 13225
8 81796
9 516961
10 3392964
11 22714756
12 155900196
13 1087218729
14 7710771721
15 55404215161
16 403030713409
17 2962388303281
18 21983682632976
19 164512124707984
20 1240577449436224