1/4 the number of (n+1)X(n+1) 0..3 symmetric matrices with every 2X2 subblock having one, three or four distinct values.
A211108
1/4 the number of (n+1)X(n+1) 0..3 symmetric matrices with every 2X2 subblock having one, three or four distinct values.
Terms
- a(0) =7a(1) =145a(2) =8869a(3) =1551481a(4) =784712137
External references
- oeis: A211108