a(n) is the first Zagreb index of the Lucas cube Lambda(n).

Terms

a(0) =0a(1) =6a(2) =12a(3) =40a(4) =90a(5) =216a(6) =462a(7) =976a(8) =1980a(9) =3940a(10) =7678a(11) =14736a(12) =27898a(13) =52220a(14) =96780a(15) =177824a(16) =324258a(17) =587304a(18) =1057350a(19) =1893320a(20) =3373692a(21) =5984924a(22) =10574342a(23) =18613920a(24) =32654450a(25) =57106036a(26) =99576972a(27) =173166616a(28) =300385770a(29) =519849720