A109897


Group the natural numbers so that every 2nth group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the product of terms in the 2nth group.


3


%I
%S 120,55440,253955520,4475671200,33891580800,7146019520640,
%T 106137499051584000,240679032790296606105600,74684882115043200,
%U 230656425830328960,66654064122818055916032000,171176782669200,282328002094320,126639913316232476160000,859891329773280
%N Group the natural numbers so that every 2nth group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the product of terms in the 2nth group.
%e a(2) = 7*8*9*10*11 = 55440.
%o (PARI) m=1;for(k=2,150,if(m%k==0,print1(m", ");m=1,m*=k))
%Y Cf. A079759, A109895, A109896.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Jul 13 2005
%E Terms from a(5) from _Franklin T. AdamsWatters_, Jun 26 2011
