Number of 0..2 arrays of length n with each element differing from at least one neighbor by 1 or less, starting with 0.

A221677

Number of 0..2 arrays of length n with each element differing from at least one neighbor by 1 or less, starting with 0.

Terms

    a(0) =0a(1) =2a(2) =5a(3) =14a(4) =40a(5) =113a(6) =320a(7) =906a(8) =2565a(9) =7262a(10) =20560a(11) =58209a(12) =164800a(13) =466578a(14) =1320965a(15) =3739886a(16) =10588280a(17) =29977297a(18) =84871040a(19) =240284954a(20) =680289285a(21) =1926019518a(22) =5452902560a(23) =15438133441a(24) =43708091520a(25) =123745352482a(26) =350345021445

External references