a(n) = (A000045(n)-A173432(n))/2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =4a(6) =6a(7) =10a(8) =16a(9) =27a(10) =44a(11) =72a(12) =116a(13) =188a(14) =304a(15) =493a(16) =798a(17) =1292a(18) =2090a(19) =3382a(20) =5472a(21) =8855a(22) =14328a(23) =23184a(24) =37512a(25) =60696a(26) =98208a(27) =158905a(28) =257114a(29) =416020