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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. 16
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 (list; graph; refs; listen; history; text; internal format)
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
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

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Last modified March 28 07:33 EDT 2024. Contains 371235 sequences. (Running on oeis4.)