a(n) = 2 * A285917(n) for n >=2, a(0) = a(1) = 0.

Terms

a(0) =0a(1) =0a(2) =2a(3) =12a(4) =22a(5) =60a(6) =104a(7) =252a(8) =438a(9) =1020a(10) =1792a(11) =4092a(12) =7264a(13) =16380a(14) =29332a(15) =65532a(16) =118198a(17) =262140a(18) =475664a(19) =1048572a(20) =1912392a(21) =4194300a(22) =7683172a(23) =16777212a(24) =30850272a(25) =67108860a(26) =123817124a(27) =268435452a(28) =496754308a(29) =1073741820