a(n) = A259708(n,n-1).

Terms

a(0) =0a(1) =-1a(2) =0a(3) =4a(4) =22a(5) =78a(6) =240a(7) =679a(8) =1828a(9) =4762a(10) =12132a(11) =30432a(12) =75504a(13) =185875a(14) =455040a(15) =1109540a(16) =2697698a(17) =6545670a(18) =15859128a(19) =38384099a(20) =92832716a(21) =224399570a(22) =542226888a(23) =1309862496a(24) =3163659744a(25) =7640066759a(26) =18448657344a(27) =44545569508a(28) =107553559150a(29) =259675788510