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Integer part of cube root of product of first n primes.
7

%I #13 Nov 10 2017 16:34:00

%S 1,1,3,5,13,31,79,213,606,1863,5853,19505,67257,235631,850352,3194167,

%T 12434883,48949883,198812307,823245530,3440622312,14763161313,

%U 64397952985,287520444756,1321070444052,6152237618431,28838910052201

%N Integer part of cube root of product of first n primes.

%H Harvey P. Dale, <a href="/A127600/b127600.txt">Table of n, a(n) for n = 1..898</a>

%p Res:= NULL:

%p p:= 1: r:= 1:

%p for n from 1 to 50 do

%p p:=nextprime(p);

%p r:= r*p;

%p Res:= Res, floor(r^(1/3));

%p od:

%p Res; # _Robert Israel_, Nov 10 2017

%t a = {}; Do[b = 1; Do[b = b Prime[x], {x, 1, n}]; AppendTo[a, Floor[b^(1/3)]], {n, 1, 100}]; a (* _Artur Jasinski_ *)

%t Floor[Surd[#,3]]&/@Rest[FoldList[Times,1,Prime[Range[30]]]] (* _Harvey P. Dale_, Jun 23 2014 *)

%o (PARI) a(n) = sqrtnint(prod(k=1, n, prime(k)), 3); \\ _Michel Marcus_, Nov 10 2017

%Y Cf. A002110, A060797.

%K nonn

%O 1,3

%A _Artur Jasinski_, Jan 19 2007

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Last modified September 20 23:16 EDT 2024. Contains 376078 sequences. (Running on oeis4.)