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A076359 a(n) = denominator(n!/phi(n!)). 2
1, 1, 1, 1, 4, 4, 8, 8, 8, 8, 16, 16, 192, 192, 192, 192, 3072, 3072, 55296, 55296, 55296, 55296, 110592, 110592, 110592, 110592, 110592, 110592, 442368, 442368, 13271040, 13271040, 13271040, 13271040, 13271040, 13271040, 477757440 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Numerator of Product_{p<=n, p prime} (1 - 1/p). - Franz Vrabec, Jan 28 2014

LINKS

Robert Israel, Table of n, a(n) for n = 1..2926

FORMULA

a(n) = denominator(A000142(n)/A048855(n)).

a(n) = A038110(A036234(n)). - Robert Israel, Oct 18 2018

MAPLE

P:= 1: p:= 1:  v:= 1:

while p < 100 do q:= nextprime(p);

   for i from p to q-1 do A[i]:= v od;

   P:= P * (1-1/q);

   v:= numer(P);

   p:= q;

od:

seq(A[i], i=1..q-1); # Robert Israel, Oct 18 2018

MATHEMATICA

dnf[n_]:=With[{nn=n!}, Denominator[nn/EulerPhi[nn]]]; Array[dnf, 40] (* Harvey P. Dale, Feb 21 2015 *)

PROG

(PARI) a(n) = numerator(prod(p=1, n, if (isprime(p), (1-1/p), 1))); \\ Michel Marcus, Jan 28 2014

CROSSREFS

Cf. A000005, A000142, A036234, A038110, A048855, A076358.

Sequence in context: A016712 A333167 A246066 * A105675 A196054 A292135

Adjacent sequences:  A076356 A076357 A076358 * A076360 A076361 A076362

KEYWORD

easy,nonn,frac

AUTHOR

Labos Elemer, Oct 08 2002

STATUS

approved

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Last modified April 17 16:12 EDT 2021. Contains 343063 sequences. (Running on oeis4.)