Number of (n+1)X(n+1) -9..9 symmetric matrices with every 2X2 subblock having sum zero and one or three distinct values.
A211551
Number of (n+1)X(n+1) -9..9 symmetric matrices with every 2X2 subblock having sum zero and one or three distinct values.
Terms
- a(0) =151a(1) =347a(2) =697a(3) =1351a(4) =2573a(5) =4843a(6) =9101a(7) =17119a(8) =32217a(9) =61049a(10) =115711a(11) =221303a(12) =423135a(13) =816445a(14) =1574315a(15) =3060679a(16) =5945293a(17) =11628771a(18) =22724533a(19) =44657457a(20) =87680827a(21) =172920419a(22) =340748827a(23) =673800359a(24) =1331438461a(25) =2638045435a(26) =5223798103
External references
- oeis: A211551