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

A081215

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

Terms

    a(0) =1a(1) =0a(2) =1a(3) =5a(4) =41a(5) =434a(6) =5713a(7) =90075a(8) =1657009a(9) =34867844a(10) =826446281a(11) =21794641505a(12) =633095889817

External references