Number of (n+1) X (n+1) -2..2 symmetric matrices with every 2 X 2 subblock having sum zero and one, two or three distinct values.
A211116
Number of (n+1) X (n+1) -2..2 symmetric matrices with every 2 X 2 subblock having sum zero and one, two or three distinct values.
Terms
- a(0) =13a(1) =31a(2) =75a(3) =177a(4) =415a(5) =963a(6) =2227a(7) =5137a(8) =11855a(9) =27397a(10) =63483a(11) =147557a(12) =344175a(13) =805635a(14) =1892433a(15) =4460137a(16) =10544415a(17) =24999069a(18) =59419405a(19) =141550383a(20) =337872559a(21) =807871799a(22) =1934541399a(23) =4638401749a(24) =11133523165a(25) =26748531157a(26) =64314484855
External references
- oeis: A211116