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A124675 a(n) = product of the positive integers k, k<= n, such that the positive integers <= k and coprime to k are also coprime to n. 0
1, 2, 6, 8, 120, 12, 5040, 384, 324, 80, 39916800, 144, 6227020800, 672, 90, 10321920, 355687428096000, 2592, 121645100408832000, 1600, 756, 84480, 25852016738884976640000, 62208, 9000000, 1198080, 14285134080, 18816 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

The positive integers k, k <= 6, where the positive integers <= k and coprime to k are also coprime to 6, are 1,2,6. So a(6) = 1*2*6 = 12.

MATHEMATICA

f[n_] := Select[Range[n], GCD[ #, n] == 1 &]; g[n_] := Select[Range[n], Times @@ GCD[f[ # ], n] == 1 &]; Times @@@ Table[g[n], {n, 30}] (*Chandler*)

CROSSREFS

Cf. A126260, A124611.

Sequence in context: A007849 A100621 A002176 * A279258 A120709 A002689

Adjacent sequences:  A124672 A124673 A124674 * A124676 A124677 A124678

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 24 2006

EXTENSIONS

Extended by Ray Chandler, Dec 24 2006

STATUS

approved

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Last modified June 26 20:24 EDT 2019. Contains 324380 sequences. (Running on oeis4.)