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%I #8 Jul 23 2022 19:25:51
%S 0,2,4,32,128,1152,6912,73728,589824,7372800,73728000,1061683200,
%T 12740198400,208089907200,2913258700800,53271016243200,
%U 852336259891200,17259809262796800,310676566730342400,6903923705118720000,138078474102374400000,3341499073277460480000
%N Bishops on an n X n board (see Robinson paper for details).
%D R. W. Robinson, Counting arrangements of bishops, pp. 198-214 of Combinatorial Mathematics IV (Adelaide 1975), Lect. Notes Math., 560 (1976). (C_{2n+1}, Eq. (20))
%H R. W. Robinson, <a href="/A000899/a000899_1.pdf">Counting arrangements of bishops</a>, pp. 198-214 of Combinatorial Mathematics IV (Adelaide 1975), Lect. Notes Math., 560 (1976). (Annotated scanned copy)
%p C:=proc(n) local k; if n mod 2 = 0 then RETURN(0); fi; k:=(n-1)/2; if k mod 2 = 0 then RETURN( k*2^(k-1)*((k/2)!)^2 ); else RETURN( 2^k*(((k+1)/2)!)^2 ); fi; end; [seq(C(2*n+1),n=0..30)];
%t c[n_] := Module[{k}, If[Mod[n, 2] == 0, 0, k = (n-1)/2; If[Mod[k, 2] == 0, k*2^(k-1)*((k/2)!)^2, 2^k*(((k+1)/2)!)^2]]];
%t a[n_] := c[2n+1];
%t Table[a[n], {n, 0, 30}] (* _Jean-François Alcover_, Jul 23 2022, after Maple code *)
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Sep 25 2006
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