Column 1 of triangle A318945.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =19a(6) =64a(7) =201a(8) =603a(9) =1752a(10) =4973a(11) =13871a(12) =38176a(13) =103985a(14) =280947a(15) =754216a(16) =2014469a(17) =5358823a(18) =14209456a(19) =37580841a(20) =99188427a(21) =261360696a(22) =687777245a(23) =1808000351a(24) =4748806720a(25) =12464634209a(26) =32699621859a(27) =85747477576a(28) =224777691893a(29) =589072137367