Half the number of n X n symmetric binary matrices with adjacent rows differing in at most two positions.

A140177

Half the number of n X n symmetric binary matrices with adjacent rows differing in at most two positions.

Terms

    a(0) =1a(1) =4a(2) =25a(3) =171a(4) =1024a(5) =5452a(6) =27319a(7) =133343a(8) =650240a(9) =3183136a(10) =15730003a(11) =78792479a(12) =401274724

External references