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Product of next n composite numbers.
3

%I #14 Apr 16 2025 04:57:14

%S 4,48,1080,60480,5544000,622702080,106661318400,28405593216000,

%T 8247280940236800,3294906785089920000,1595754032207182848000,

%U 840201424492187197440000,653671274699431372640256000

%N Product of next n composite numbers.

%H Harvey P. Dale, <a href="/A071221/b071221.txt">Table of n, a(n) for n = 1..224</a>

%e a(1) = 4,a(2) = 6*8 = 48 and a(3) = 9*10*12 = 1080.

%t nn=15;With[{comps=Complement[Rest[Range[(nn(nn+1))]],Prime[Range[ PrimePi[ (nn(nn+1))]]]]},Table[Times@@Take[comps,{(n(n-1))/2+1,(n(n+1))/2}],{n,nn}]] (* _Harvey P. Dale_, Dec 03 2012 *)

%t Module[{nn=200,cmps,len},cmps=Select[Range[nn],CompositeQ];len=Floor[(Sqrt[8 Length[cmps]+1]-1)/2];Times@@@TakeList[cmps,Range[len]]] (* _Harvey P. Dale_, May 25 2022 *)

%K nonn

%O 1,1

%A _Amarnath Murthy_, May 17 2002

%E Corrected and extended by _Lior Manor_, Jun 02 2002