a(n) = 2*(2*n+1)*A000538(n) - 4*A000330(n)^2.

Terms

a(0) =0a(1) =2a(2) =70a(3) =588a(4) =2772a(5) =9438a(6) =26026a(7) =61880a(8) =131784a(9) =257754a(10) =471086a(11) =814660a(12) =1345500a(13) =2137590a(14) =3284946a(15) =4904944a(16) =7141904a(17) =10170930a(18) =14202006a(19) =19484348a(20) =26311012a(21) =35023758a(22) =46018170a(23) =59749032a(24) =76735960a(25) =97569290a(26) =122916222a(27) =153527220a(28) =190242668a(29) =233999782