Number of nX2 zero-sum -2..2 arrays with rows and columns lexicographically nondecreasing.

A201490

Number of nX2 zero-sum -2..2 arrays with rows and columns lexicographically nondecreasing.

Terms

    a(0) =3a(1) =29a(2) =226a(3) =1454a(4) =7815a(5) =36487a(6) =151593a(7) =571539a(8) =1982705a(9) =6399842a(10) =19389074a(11) =55531190a(12) =151238480a(13) =393631919a(14) =983211316a(15) =2365399764a(16) =5498241469a(17) =12382111994a(18) =27080912704a(19) =57644263473a(20) =119645822176a(21) =242563511707

External references