|
%I #10 Dec 19 2021 10:58:01
%S 0,0,0,0,0,0,0,3,0,0,0,40,0,0,3003,105,0,71680,0,24192,2078505,0,0,
%T 330,4216455243,0,2788660875,39536640,0,256256,0,16380,6153560492625,
%U 0,276348105,15841280,0,0,20228646742486875,1116288,0,1190707200,0
%N a(n) is the least integer of the form (n-2)(n-4)...(n-2k)/n. 0 if no such number exists.
%C a(n) = 0 if n = 1,9, p or 2*p, p is a prime. This is not exhaustive.
%e a(12) = 10*8*6/12 = 40, a(15) = 13*11*9*7*5/15 = 3003.
%o (PARI) a(n) = pp=n-2;k=1;while((n-2*k>0) && ((pp % n)>0),k=k+1;pp=pp*(n-2*k));if( ((pp%n)==0) && (pp>0),return(pp/n),return(0)); \\ _Matthew Conroy_, Mar 28 2006
%Y Cf. A109899.
%K nonn
%O 1,8
%A _Amarnath Murthy_, Jul 13 2005
%E More terms from _Matthew Conroy_, Mar 28 2006
|
