A076359 a(n) = denominator(n!/phi(n!)).

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

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: A346062 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