a(n) = n^n - (n+1)!/2.

A345445

a(n) = n^n - (n+1)!/2.

Terms

    a(0) =0a(1) =1a(2) =15a(3) =196a(4) =2765a(5) =44136a(6) =803383a(7) =16595776a(8) =385606089a(9) =9980041600a(10) =285072169811

External references