Number of (n+1) X (n+1) -9..9 symmetric matrices with every 2 X 2 subblock having sum zero and one or two distinct values.
A211549
Number of (n+1) X (n+1) -9..9 symmetric matrices with every 2 X 2 subblock having sum zero and one or two distinct values.
Terms
- a(0) =31a(1) =43a(2) =61a(3) =91a(4) =139a(5) =217a(6) =343a(7) =547a(8) =877a(9) =1411a(10) =2275a(11) =3673a(12) =5935a(13) =9595a(14) =15517a(15) =25099a(16) =40603a(17) =65689a(18) =106279a(19) =171955a(20) =278221a(21) =450163a(22) =728371a(23) =1178521a(24) =1906879a(25) =3085387a(26) =4992253a(27) =8077627a(28) =13069867a(29) =21147481
External references
- oeis: A211549