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A139805 A number n is included if (product{k|n, k<=sqrt(n)} k) (= A072499(n)) does not divide n. 0
20, 28, 36, 42, 44, 48, 52, 54, 60, 66, 68, 72, 76, 78, 80, 84, 88, 90, 92, 96, 99, 100, 102, 104, 108, 110, 112, 114, 116, 117, 120, 124, 126, 130, 132, 136, 138, 140, 144, 148, 150, 152, 153, 156, 160, 162, 164, 168, 170, 171, 172, 174, 176, 180, 184, 186, 188 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

The divisors of 42 that are each <= sqrt(42) are 1,2,3,6. The product of these is 36. 36 does not divide 42, so 42 is in the sequence.

MAPLE

A072499 := proc(n) local a, k ; a := 1 ; for k in numtheory[divisors](n) do if k^2 <= n then a := a*k ; fi ; od: a ; end: isA139805 := proc(n) RETURN( n mod A072499(n) <> 0 ) end: for n from 1 to 300 do if isA139805(n) then printf("%d, ", n) ; fi ; od: # R. J. Mathar, May 24 2008

MATHEMATICA

a = {}; For[n = 1, n < 200, n++, If[Mod[n, Times @@ (Select[Divisors[n], ! # > Sqrt[n] &])] > 0, AppendTo[a, n]]]; a (* Stefan Steinerberger *)

CROSSREFS

Cf. A072499.

Sequence in context: A032482 A024411 A269986 * A141823 A137428 A309769

Adjacent sequences:  A139802 A139803 A139804 * A139806 A139807 A139808

KEYWORD

nonn

AUTHOR

Leroy Quet, May 22 2008

EXTENSIONS

More terms from R. J. Mathar and Stefan Steinerberger, May 24 2008

STATUS

approved

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Last modified July 5 20:01 EDT 2020. Contains 335473 sequences. (Running on oeis4.)