1/4 the number of (2n)X(2n) 0..3 symmetric matrices with every element equal to two horizontal and vertical neighbors.
A211078
1/4 the number of (2n)X(2n) 0..3 symmetric matrices with every element equal to two horizontal and vertical neighbors.
Terms
- a(0) =1a(1) =12a(2) =408a(3) =39072a(4) =10448832a(5) =7784500224
External references
- oeis: A211078