a(n) = 2 * A000538(n).

Terms

a(0) =0a(1) =2a(2) =34a(3) =196a(4) =708a(5) =1958a(6) =4550a(7) =9352a(8) =17544a(9) =30666a(10) =50666a(11) =79948a(12) =121420a(13) =178542a(14) =255374a(15) =356624a(16) =487696a(17) =654738a(18) =864690a(19) =1125332a(20) =1445332a(21) =1834294a(22) =2302806a(23) =2862488a(24) =3526040a(25) =4307290a(26) =5221242a(27) =6284124a(28) =7513436a(29) =8927998