Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and one, three or four distinct values.

A211327

Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and one, three or four distinct values.

Terms

    a(0) =15a(1) =33a(2) =69a(3) =143a(4) =293a(5) =595a(6) =1205a(7) =2427a(8) =4885a(9) =9803a(10) =19669a(11) =39403a(12) =78933a(13) =157995a(14) =316245a(15) =632747a(16) =1266005a(17) =2532523a(18) =5066069a(19) =10133163a(20) =20268373a(21) =40538795a(22) =81081685a(23) =162167467a(24) =324343125a(25) =648694443a(26) =1297405269a(27) =2594826923a(28) =5189686613

External references