Number of (n+1)X(n+1) -7..7 symmetric matrices with every 2X2 subblock having sum zero and one or three distinct values.
A211443
Number of (n+1)X(n+1) -7..7 symmetric matrices with every 2X2 subblock having sum zero and one or three distinct values.
Terms
- a(0) =91a(1) =201a(2) =397a(3) =765a(4) =1459a(5) =2751a(6) =5215a(7) =9855a(8) =18759a(9) =35741a(10) =68529a(11) =131739a(12) =254515a(13) =493209a(14) =959339a(15) =1871379a(16) =3660547a(17) =7178105a(18) =14104015a(19) =27769453a(20) =54754733a(21) =108142387a(22) =213809725a(23) =423287363a(24) =838643733a(25) =1663340421a(26) =3300898801
External references
- oeis: A211443