Number of alternating sign 2n+1 X 2n+1 matrices symmetric with respect to both horizontal and vertical axes (VHSASM's).
A005161
Number of alternating sign 2n+1 X 2n+1 matrices symmetric with respect to both horizontal and vertical axes (VHSASM's).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =33a(6) =286a(7) =4420a(8) =109820a(9) =4799134a(10) =340879665a(11) =42235307100
External references
- oeis: A005161