Half the number of nX4 binary arrays with each element equal to at least two neighbors.

A180753

Half the number of nX4 binary arrays with each element equal to at least two neighbors.

Terms

    a(0) =0a(1) =2a(2) =2a(3) =9a(4) =21a(5) =70a(6) =207a(7) =658a(8) =2059a(9) =6521a(10) =20602a(11) =65244a(12) =206608a(13) =654594a(14) =2073996a(15) =6571885a(16) =20824917a(17) =65991668a(18) =209121585a(19) =662691890a(20) =2100031249a(21) =6654888151a(22) =21089009696a(23) =66830061534a(24) =211781324846a(25) =671125181554

External references