1/4 the number of (n+1)X(n+1) 0..3 symmetric matrices with every 2X2 subblock having two, three or four distinct values.
A211109
1/4 the number of (n+1)X(n+1) 0..3 symmetric matrices with every 2X2 subblock having two, three or four distinct values.
Terms
- a(0) =15a(1) =891a(2) =208575a(3) =192515373a(4) =700590250755
External references
- oeis: A211109