Number of (n+1)X(n+1) -4..4 symmetric matrices with every 2X2 subblock having sum zero and two or three distinct values.
A211493
Number of (n+1)X(n+1) -4..4 symmetric matrices with every 2X2 subblock having sum zero and two or three distinct values.
Terms
- a(0) =40a(1) =96a(2) =214a(3) =446a(4) =920a(5) =1852a(6) =3716a(7) =7414a(8) =14772a(9) =29486a(10) =58836a(11) =117908a(12) =236354a(13) =475986a(14) =959170a(15) =1940794a(16) =3930106a(17) =7985174a(18) =16237818a(19) =33106698a(20) =67555856a(21) =138133826a(22) =282669656a(23) =579365960a(24) =1188357854a(25) =2440574368a(26) =5015738686a(27) =10318671714
External references
- oeis: A211493