a(n) = A188491(n+1) - A188494(n) - A002526(n).

Terms

a(0) =0a(1) =0a(2) =2a(3) =4a(4) =12a(5) =32a(6) =108a(7) =336a(8) =1036a(9) =3120a(10) =9540a(11) =29244a(12) =89768a(13) =274788a(14) =840936a(15) =2573972a(16) =7881922a(17) =24135000a(18) =73897320a(19) =226249264a(20) =692714696a(21) =2120941424a(22) =6493883944a(23) =19882820480a(24) =60876609464a(25) =186390208744a(26) =570684661408