Number of 0..3 arrays of length n with each element differing from at least one neighbor by 2 or more, starting with 0.

A221510

Number of 0..3 arrays of length n with each element differing from at least one neighbor by 2 or more, starting with 0.

Terms

    a(0) =0a(1) =2a(2) =3a(3) =12a(4) =30a(5) =89a(6) =248a(7) =706a(8) =1995a(9) =5652a(10) =15998a(11) =45297a(12) =128240a(13) =363074a(14) =1027923a(15) =2910236a(16) =8239390a(17) =23327177a(18) =66043368a(19) =186980482a(20) =529374875a(21) =1498754084a(22) =4243238398a(23) =12013359841a(24) =34011950560a(25) =96293859202a(26) =272624979363

External references