This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A003047 M1993 #34 Oct 20 2023 22:34:08
%S A003047 1,1,2,10,280,235200,173859840000,98238542885683200000000,
%T A003047 32169371027674057560745102540800000000000000000,
%U A003047 3518552669874927170883258602839130084576857453953842493259776000000000000000000000000000000000
%N A003047 a(n) = Catalan(n) * Product_{k = 0..n-1} a(k).
%D A003047 D.-Z. Du and F. K. Hwang, Combinatorial Group Testing and Its Applications, World Scientific, 2nd ed., 2000; p. 36.
%D A003047 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A003047 J. W. Moon, R. K. Guy, and N. J. A. Sloane, <a href="/A003046/a003046.pdf">Correspondence, 1973</a>.
%H A003047 J. W. Moon and M. Sobel, <a href="https://doi.org/10.1016/0095-8956(77)90030-2">Enumerating a class of nested group testing procedures</a>, J. Combin. Theory, B23 (1977), 184-188.
%F A003047 a(n) = ((4*n-6)*a(n-1)^2)/n, for n > 1. - _Christian Krause_, Oct 13 2023
%Y A003047 See A028580 for another version. Cf. A000108, A003046.
%K A003047 easy,nonn
%O A003047 1,3
%A A003047 _N. J. A. Sloane_