Number of directed column-convex polyominoes of height n: a(k+1)=(k+1)*a(k)+(a(1)+...+a(k)).

A007808

Number of directed column-convex polyominoes of height n: a(k+1)=(k+1)*a(k)+(a(1)+...+a(k)).

Terms

    a(0) =1a(1) =1a(2) =3a(3) =13a(4) =69a(5) =431a(6) =3103a(7) =25341a(8) =231689a(9) =2345851a(10) =26065011a(11) =315386633a(12) =4128697741a(13) =58145826519a(14) =876660153671

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