Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 20.

A156474

Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 20.

Terms

    a(0) =4a(1) =7a(2) =78a(3) =660a(4) =19896a(5) =352350a(6) =29182380a(7) =1150637340a(8) =215977376730

External references