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A261130 a(n) = Product(p prime | n < p <= 2*n). 2

%I

%S 1,2,3,5,35,7,77,143,143,2431,46189,4199,96577,7429,7429,215441,

%T 6678671,392863,392863,765049,765049,31367009,1348781387,58642669,

%U 2756205443,2756205443,2756205443,146078888479,146078888479,5037203051,297194980009,584803025179

%N a(n) = Product(p prime | n < p <= 2*n).

%C Essentially the same as A068111. - _R. J. Mathar_, Nov 23 2015

%e a(0) = 1 because the empty product is 1 by convention.

%e a(4) = 35 because {p prime | 4 < p <= 8} = {5, 7}.

%p a := n -> convert(select(isprime, {$n+1..2*n}),`*`):

%p print(seq(a(n), n=0..31));

%t Join[{1},Table[Times@@Prime[Range[PrimePi[n]+1,PrimePi[2n]]],{n,40}]] (* _Harvey P. Dale_, May 09 2017 *)

%o (PARI) A261130(n,P=1)={forprime(p=n+1,2*n,P*=p);P} \\ _M. F. Hasler_, Nov 25 2015

%Y Cf. A034386.

%K nonn

%O 0,2

%A _Peter Luschny_, Oct 31 2015

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Last modified October 23 22:51 EDT 2019. Contains 328378 sequences. (Running on oeis4.)