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A096366 Known primitive friendly integers. 6
6, 12, 24, 28, 30, 40, 42, 56, 60, 80, 84, 96, 108, 135, 140, 168, 200, 210, 224, 234, 240, 264, 270, 273, 480, 496 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

There may be other primitive friendly integers within the range of those given, but they have yet to be calculated.

All perfect numbers are 2-primitive-friendly (since they are all products of distinct powers of 2 and distinct Mersenne primes). - Daniel Forgues, Jun 24 2009

REFERENCES

Anderson, Claude W. and Hickerson, Dean; Advanced Problem 6020, "Friendly Integers", Amer. Math. Monthly, 1977, V84#1p65-6.

Hickerson, Dean; "Re: Friendly number", post to sci.math newsgroup, 2000, available through groups.google.com.

LINKS

Table of n, a(n) for n=0..25.

Walter Nissen, Primitive Friendly Integers and Exclusive Multiples, 2004 post to NMBRTHRY mailing list

FORMULA

Friends m and n are primitive friendly iff they have no common prime factor of the same multiplicity.

EXAMPLE

While 6 and 28 are not coprime because they share the common factor 2, the factor 2 appears twice in 28 but only once in 6, so they are in the sequence.

CROSSREFS

Cf. A014567, A074902, A095738, A095739.

Sequence in context: A096387 A094185 A074902 * A247145 A188158 A061822

Adjacent sequences:  A096363 A096364 A096365 * A096367 A096368 A096369

KEYWORD

nonn

AUTHOR

Walter Nissen, Jul 01 2004

STATUS

approved

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Last modified June 25 00:41 EDT 2017. Contains 288708 sequences.