Number of (n+1)X(n+1) -8..8 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.
A211470
Number of (n+1)X(n+1) -8..8 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.
Terms
- a(0) =145a(1) =397a(2) =945a(3) =2153a(4) =4775a(5) =10527a(6) =22995a(7) =50565a(8) =110915a(9) =245927a(10) =545909a(11) =1225707a(12) =2760503a(13) =6282475a(14) =14352999a(15) =33082005a(16) =76545031a(17) =178364381a(18) =417062331a(19) =980496727a(20) =2311774857a(21) =5472654325a(22) =12985260305a(23) =30901798587a(24) =73669894089
External references
- oeis: A211470