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 A028580 #13 Jul 02 2025 16:01:56
%S A028580 1,2,10,280,235200,173859840000,98238542885683200000000,
%T A028580 32169371027674057560745102540800000000000000000,
%U A028580 3518552669874927170883258602839130084576857453953842493259776000000000000000000000000000000000
%N A028580 C_{n+1}*C_n*C_{n-1}^2*C_{n-2}^4*...*C_2^{2^(n-2)}, where C_k are the Catalan numbers (A000108).
%C A028580 Essentially the same as A003047, which is the main entry. [From _R. J. Mathar_, Oct 23 2008]
%D A028580 D.-Z. Du and F. K. Hwang, Combinatorial Group Testing and Its Applications, World Scientific, 2nd ed., 2000; p. 36.
%F A028580 a(n) = 2*(2n-1)*a(n-1)^2/(n+1).
%t A028580 RecurrenceTable[{a[n] == 2*(2*n-1)*a[n-1]^2/(n+1), a[1]==1}, a, {n, 1, 10}] (* _Vaclav Kotesovec_, Mar 07 2019 *)
%Y A028580 Cf. A003047, A000108.
%K A028580 nonn,easy
%O A028580 1,2
%A A028580 _N. J. A. Sloane_, May 22 2000
%E A028580 More terms from _James Sellers_, May 22 2000