Number of (n+1) X (n+1) -4..4 symmetric matrices with every 2 X 2 subblock having sum zero and one or two distinct values.

A211490

Number of (n+1) X (n+1) -4..4 symmetric matrices with every 2 X 2 subblock having sum zero and one or two distinct values.

Terms

    a(0) =13a(1) =17a(2) =23a(3) =33a(4) =49a(5) =75a(6) =117a(7) =185a(8) =295a(9) =473a(10) =761a(11) =1227a(12) =1981a(13) =3201a(14) =5175a(15) =8369a(16) =13537a(17) =21899a(18) =35429a(19) =57321a(20) =92743a(21) =150057a(22) =242793a(23) =392843a(24) =635629a(25) =1028465a(26) =1664087a(27) =2692545a(28) =4356625a(29) =7049163

External references