

A125490


Amicable triples: numbers such that sigma(x) = sigma(y) = sigma(z) = x+y+z, x<y<z. We order these triples according to the common value of sigma. Sequence gives x numbers.


19



1980, 9180, 21168, 23940, 37380, 38940, 38940, 39480, 46368, 47124, 53088, 57420, 66720, 67860, 69720, 73320, 75180, 77490, 72072, 86040, 93456, 96660, 92820, 100980, 100980, 112140, 118944, 121800, 139080, 141372
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OFFSET

1,1


COMMENTS

G. Resta computed these terms.
As stated, we first order by common sigma value. When the common value of sigma is the same for several triples, these are then sorted (ascending) by the smallest member. When the smallest members also agree, we go on to the second smallest members, and so on, lexicographically.  John Cerkan, Jun 18 2016


LINKS

John Cerkan, Table of n, a(n) for n = 1..10000 [Terms 1 through 1000 were computed by Donovan Johnson]


EXAMPLE

1980 is in the sequence since sigma(1980) = sigma(2016) = sigma(2556) = 6552 = 1980 + 2016 + 2556.  Michael B. Porter, Jun 29 2016


CROSSREFS

Cf. A125491, A125492, A137231 (x+y+z).
Cf. A036471  A036474 and A116148 (amicable quadruples).
Cf. A233553 for amicable 5tuples.
Cf. A000203 (sigma function).
Sequence in context: A343972 A225235 A289907 * A237334 A035870 A345517
Adjacent sequences: A125487 A125488 A125489 * A125491 A125492 A125493


KEYWORD

nonn


AUTHOR

Yasutoshi Kohmoto, Dec 11 2006


EXTENSIONS

Definition corrected by N. J. A. Sloane, Nov 27 2008
a(13)a(30) from Donovan Johnson, Apr 14 2010


STATUS

approved



