Number of nX4 0..1 arrays with every element equal to 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.

A301819

Number of nX4 0..1 arrays with every element equal to 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.

Terms

    a(0) =2a(1) =8a(2) =25a(3) =68a(4) =177a(5) =457a(6) =1183a(7) =3075a(8) =8018a(9) =20947a(10) =54782a(11) =143348a(12) =375200a(13) =982178a(14) =2571247a(15) =6731462a(16) =17623023a(17) =46137475a(18) =120789253a(19) =316230117a(20) =827900912a(21) =2167472413a(22) =5674516100a(23) =14856075638a(24) =38893710542a(25) =101825055692a(26) =266581456213

External references