Number of (n+1) X (n+1) -10..10 symmetric matrices with every 2 X 2 subblock having sum zero and two distinct values.

A211813

Number of (n+1) X (n+1) -10..10 symmetric matrices with every 2 X 2 subblock having sum zero and two distinct values.

Terms

    a(0) =32a(1) =44a(2) =62a(3) =92a(4) =140a(5) =218a(6) =344a(7) =548a(8) =878a(9) =1412a(10) =2276a(11) =3674a(12) =5936a(13) =9596a(14) =15518a(15) =25100a(16) =40604a(17) =65690a(18) =106280a(19) =171956a(20) =278222a(21) =450164a(22) =728372a(23) =1178522a(24) =1906880a(25) =3085388a(26) =4992254a(27) =8077628a(28) =13069868a(29) =21147482

External references