A003047 a(n) = Catalan(n) * Product_{k = 0..n-1} a(k). (Formerly M1993)

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

Offset

1,3

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

Table of n, a(n) for n=1..10.

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.

Formula

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

Crossrefs

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

Sequence in context: A144288 A215286 A260231 * A028580 A171873 A098706

Adjacent sequences: A003044 A003045 A003046 * A003048 A003049 A003050

Keyword

easy,nonn

Author

N. J. A. Sloane

Status

approved