# A012321 (b-file synthesized from sequence entry) 0 0 1 1 2 2 3 5 4 20 5 125 6 830 7 6001 8 45768 9 394553 10 3699418 11 38758909 12 433324828 13 5299232757 14 68428221654 15 958395448297 16 14101599762448 17 223667919165041 18 3706771205012274 19 65843651814440309 20 1215858569345385636