A125492 - OEIS

A125492

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 z numbers.

2556, 11556, 27312, 32136, 42168, 41952, 41412, 54870, 55890, 57834, 54516, 70110, 75540, 83772, 88480, 84348, 84504, 83538, 102258, 100890, 100656, 108324, 138828, 132792, 132396, 143370, 146268, 168150, 162384, 189948

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OFFSET

1,1

COMMENTS

Giovanni Resta computed the first 12 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

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

CROSSREFS

Cf. A125490, A125491, A137231 (x+y+z).

Cf. A000203 (sigma function).

Sequence in context: A255037 A256948 A202587 * A309042 A170794 A068265

Adjacent sequences: A125489 A125490 A125491 * A125493 A125494 A125495

KEYWORD

nonn

AUTHOR

Yasutoshi Kohmoto, Dec 11 2006

EXTENSIONS

a(1)-a(12) from Giovanni Resta

Definition corrected by N. J. A. Sloane, Nov 27 2008

a(13)-a(30) from Donovan Johnson, Apr 14 2010

STATUS

approved