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Product of first n single (i.e., non-twin) primes.
1

%I #12 Nov 02 2021 11:35:49

%S 2,46,1702,79994,4239682,284058694,22440636826,1862572856558,

%T 165768984233662,16079591470665214,1816993836185169182,

%U 230758217195516486114,30229326452612659680934,4746004253060187569906638,773598693248810573894781994

%N Product of first n single (i.e., non-twin) primes.

%C a(n) = 5*A002110(A049084(A074038(n)))/A074040(k), where k is the largest number such that A006512(k) < A007510(n).

%F a(1) = A007510(1) and a(n) = a(n-1)*A007510(n) for n > 1.

%e The first four single primes are 2, 23, 37 and 47, therefore a(4) = 2*23*37*47 = 79994.

%t nn=50;tps=Union[Flatten[Select[Partition[Prime[Range[nn]],2,1],Last[#]- First[#] ==2&]]]; ntps=Complement[Prime[Range[nn]],tps];Rest[ FoldList[ Times,1,ntps]] (* _Harvey P. Dale_, Mar 31 2011 *)

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Aug 13 2002

%E More terms from _Harvey P. Dale_, Mar 31 2011