Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 4.

A156436

Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 4.

Terms

    a(0) =1a(1) =0a(2) =0a(3) =3a(4) =5a(5) =12a(6) =54a(7) =426a(8) =2334a(9) =23280a(10) =152820a(11) =1939740a(12) =14564760a(13) =222925920a(14) =1890254100a(15) =33899743010a(16) =320743643010

External references