# A074187 (b-file synthesized from sequence entry) 1 1 2 1 3 4 4 16 5 100 6 676 7 4913 8 40000 9 362404 10 3625216 11 39904489 12 478996996 13 6226945921 14 87177877081 15 1307672296225 16 20922784184449 17 355687416544329 18 6402373660047556 19 121645099966283776 20 2432902006216007824