A003047 a(n) = Catalan(n) * Product_{k = 0..n-1} a(k).

1, 1, 2, 10, 280, 235200, 173859840000, 98238542885683200000000, 32169371027674057560745102540800000000000000000, 3518552669874927170883258602839130084576857453953842493259776000000000000000000000000000000000

Offset: 1

Author

N. J. A. Sloane

Keywords

• easy
• nonn

References

• D.-Z. Du and F. K. Hwang, Combinatorial Group Testing and Its Applications, World Scientific, 2nd ed., 2000; p. 36.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• J. W. Moon, R. K. Guy, and N. J. A. Sloane, Correspondence, 1973.
• J. W. Moon and M. Sobel, Enumerating a class of nested group testing procedures, J. Combin. Theory, B23 (1977), 184-188.

Crossrefs

See A028580 for another version. Cf. A000108, A003046.

Formula

a(n) = ((4*n-6)*a(n-1)^2)/n, for n > 1. - Christian Krause, Oct 13 2023