Number of (n+1) X (n+1) -6..6 symmetric matrices with every 2 X 2 subblock having sum zero and one or two distinct values.

A211253

Number of (n+1) X (n+1) -6..6 symmetric matrices with every 2 X 2 subblock having sum zero and one or two distinct values.

Terms

    a(0) =21a(1) =29a(2) =41a(3) =61a(4) =93a(5) =145a(6) =229a(7) =365a(8) =585a(9) =941a(10) =1517a(11) =2449a(12) =3957a(13) =6397a(14) =10345a(15) =16733a(16) =27069a(17) =43793a(18) =70853a(19) =114637a(20) =185481a(21) =300109a(22) =485581a(23) =785681a(24) =1271253a(25) =2056925a(26) =3328169a(27) =5385085a(28) =8713245a(29) =14098321

External references