Number of nX2 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1.

A204078

Number of nX2 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1.

Terms

    a(0) =0a(1) =4a(2) =4a(3) =16a(4) =100a(5) =324a(6) =1296a(7) =5476a(8) =21316a(9) =85264a(10) =343396a(11) =1368900a(12) =5475600a(13) =21921124a(14) =87647044a(15) =350588176a(16) =1402502500a(17) =5609710404a(18) =22438841616a(19) =89756564836a(20) =359023862596

External references