Number of n X 2 0..3 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 4, and upper left element zero.

A230245

Number of n X 2 0..3 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 4, and upper left element zero.

Terms

    a(0) =0a(1) =2a(2) =6a(3) =26a(4) =118a(5) =522a(6) =2310a(7) =10234a(8) =45334a(9) =200810a(10) =889510a(11) =3940186a(12) =17453494a(13) =77312202a(14) =342463046a(15) =1516978362a(16) =6719625302a(17) =29765331754a(18) =131848865766a(19) =584039296026

External references