Number of (n+1) X (n+1) -11..11 symmetric matrices with every 2 X 2 subblock having sum zero and two or four distinct values.
A211715
Number of (n+1) X (n+1) -11..11 symmetric matrices with every 2 X 2 subblock having sum zero and two or four distinct values.
Terms
- a(0) =34a(1) =58a(2) =106a(3) =202a(4) =394a(5) =778a(6) =1546a(7) =3082a(8) =6154a(9) =12298a(10) =24586a(11) =49162a(12) =98314a(13) =196618a(14) =393226a(15) =786442a(16) =1572874a(17) =3145738a(18) =6291466a(19) =12582922a(20) =25165834a(21) =50331658a(22) =100663306a(23) =201326602a(24) =402653194a(25) =805306378a(26) =1610612746a(27) =3221225482
External references
- oeis: A211715