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%I #11 Nov 07 2023 11:17:56
%S 0,0,0,0,0,2,12,70,448,3298,27490,255876,2631876,29652480,363242880,
%T 4807626352,68375130352,1040021719578,16848351857178,289631191449600,
%U 5266021662720000,100970241446066086,2036233202495666086,43086694564808294400,954536002666522214400,22095740802465792000000
%N Floor((n-1)!/[n(n+1)]).
%C All terms are even.
%D T. Andreescu, D. Andrica and Z. Feng, 104 Number Theory Problems (from the training of the USA IMO team), Birkhäuser, Boston, 2007, Introductory problem # 50, pp. 82,126,127.
%p seq(floor(factorial(n-1)/(n*(n+1))),n=1..25);
%t Table[Floor[(n-1)!/(n(n+1))],{n,30}] (* _Harvey P. Dale_, Apr 11 2012 *)
%K nonn
%O 1,6
%A _Emeric Deutsch_, Aug 11 2008
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