a(n) = (n!)^2 - n^n.A135609a(n) = (n!)^2 - n^n.Terms a(0) =0a(1) =0a(2) =0a(3) =9a(4) =320a(5) =11275a(6) =471744a(7) =24578057a(8) =1608925184a(9) =131294473911External referencesoeis: A135609