Number of (n+1)X(n+1) -4..4 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.
A211494
Number of (n+1)X(n+1) -4..4 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.
Terms
- a(0) =41a(1) =105a(2) =259a(3) =619a(4) =1455a(5) =3389a(6) =7821a(7) =18047a(8) =41509a(9) =95753a(10) =220953a(11) =511805a(12) =1187991a(13) =2768195a(14) =6468085a(15) =15166639a(16) =35663339a(17) =84116703a(18) =198906647a(19) =471540601a(20) =1120285205a(21) =2667019663a(22) =6360447181a(23) =15193138613a(24) =36342090585a(25) =87038546365
External references
- oeis: A211494