a(n) = (n^n - 3*(n-1)^n + 3*(n-2)^n - (n-3)^n)/6.
A281595
a(n) = (n^n - 3*(n-1)^n + 3*(n-2)^n - (n-3)^n)/6.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =1a(4) =10a(5) =125a(6) =1890a(7) =33621a(8) =688506a(9) =15958405a(10) =413066170a(11) =11810819141a(12) =369730963602
External references
- oeis: A281595