a(n) = 0^n + 3*((n+2)^n/(n+3) - (-1)^n/(n+3)).

A091760

a(n) = 0^n + 3*((n+2)^n/(n+3) - (-1)^n/(n+3)).

Terms

    a(0) =1a(1) =3a(2) =9a(3) =63a(4) =555a(5) =6303a(6) =87381a(7) =1434891a(8) =27272727a(9) =589486923a(10) =14288622513a(11) =384034370151

External references