# A058381 (b-file synthesized from sequence entry) 0 0 1 1 2 1 3 4 4 20 5 156 6 1472 7 17396 8 239612 9 3827816 10 69071272 11 1394315088 12 31081310944 13 758901184432 14 20135117147056 15 576927779925568 16 17752780676186432 17 583910574851160000 18 20443098012485430272 19 759064322969950283072 20 29793617955495321025472