2-enumeration of 2n X 2n half-turn symmetric alternating-sign matrices.
A057170
2-enumeration of 2n X 2n half-turn symmetric alternating-sign matrices.
Terms
- a(0) =1a(1) =2a(2) =12a(3) =288a(4) =26880a(5) =10035200a(6) =14836039680
External references
- oeis: A057170