Number of (n+1)X(n+1) -11..11 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.
A211714
Number of (n+1)X(n+1) -11..11 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.
Terms
- a(0) =265a(1) =747a(2) =1781a(3) =4001a(4) =8773a(5) =18947a(6) =40653a(7) =87497a(8) =187925a(9) =408201a(10) =886709a(11) =1954227a(12) =4312823a(13) =9660215a(14) =21682565a(15) =49330249a(16) =112485053a(17) =259451281a(18) =599683373a(19) =1398909233a(20) =3268979199a(21) =7693687203a(22) =18131925659a(23) =42963258607a(24) =101902441855
External references
- oeis: A211714