Number of (n+1)X(n+1) -7..7 symmetric matrices with every 2X2 subblock having sum zero and two or three distinct values.
A211444
Number of (n+1)X(n+1) -7..7 symmetric matrices with every 2X2 subblock having sum zero and two or three distinct values.
Terms
- a(0) =112a(1) =294a(2) =656a(3) =1404a(4) =2890a(5) =5896a(6) =11792a(7) =23678a(8) =46864a(9) =93614a(10) =184790a(11) =368876a(12) =728858a(13) =1457004a(14) =2886784a(15) =5784714a(16) =11502262a(17) =23114684a(18) =46139666a(19) =92997430a(20) =186362182a(21) =376728674a(22) =757813990a(23) =1536216028a(24) =3101292166a(25) =6303428906a(26) =12767750824
External references
- oeis: A211444