a(n) = -Sum_{k=1..3}(-1)^(n-k)*hypergeom([k, k-n-3], [], 1).

A292897

a(n) = -Sum_{k=1..3}(-1)^(n-k)*hypergeom([k, k-n-3], [], 1).

Terms

    a(0) =3a(1) =7a(2) =27a(3) =129a(4) =755a(5) =5187a(6) =40923a(7) =364333a(8) =3611811a(9) =39448095a(10) =470573723a(11) =6086754297a(12) =84847445907

External references