Number of nX1 0..3 arrays with exactly floor(nX1/2) elements equal to at least one king-move neighbor, with new values introduced in row major 0..3 order.

A222604

Number of nX1 0..3 arrays with exactly floor(nX1/2) elements equal to at least one king-move neighbor, with new values introduced in row major 0..3 order.

Terms

    a(0) =1a(1) =0a(2) =0a(3) =6a(4) =20a(5) =20a(6) =70a(7) =685a(8) =2808a(9) =5370a(10) =21294a(11) =123410a(12) =514792a(13) =1341616a(14) =5472216a(15) =25106526a(16) =105042770a(17) =321557310a(18) =1329068686a(19) =5447475968a(20) =22826820144a(21) =76079350800a(22) =316839140020

External references