Number of crossing set partitions of {1,2,...,n}.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =10a(6) =71a(7) =448a(8) =2710a(9) =16285a(10) =99179a(11) =619784a(12) =4005585a(13) =26901537a(14) =188224882a(15) =1373263700a(16) =10444784477a(17) =82735225014a(18) =681599167459