Arises in covering a graph by forests and a matching.

Terms

a(0) =2a(1) =12a(2) =52a(3) =140a(4) =294a(5) =532a(6) =872a(7) =1332a(8) =1930a(9) =2684a(10) =3612a(11) =4732a(12) =6062a(13) =7620a(14) =9424a(15) =11492a(16) =13842a(17) =16492a(18) =19460a(19) =22764a(20) =26422a(21) =30452a(22) =34872a(23) =39700a(24) =44954a(25) =50652a(26) =56812a(27) =63452a(28) =70590a(29) =78244