Number of maximal 2-independent sets in the planar 3 X n grid graph.

Terms

a(0) =0a(1) =3a(2) =4a(3) =11a(4) =17a(5) =36a(6) =69a(7) =133a(8) =254a(9) =499a(10) =959a(11) =1852a(12) =3589a(13) =6943a(14) =13410a(15) =25951a(16) =50197a(17) =97050a(18) =187699a(19) =363047a(20) =702066a(21) =1357755a(22) =2625947a(23) =5078438a(24) =9821417a(25) =18994465a(26) =36734648a(27) =71043261a(28) =137395463a(29) =265718350