A125490 Amicable triples: numbers such that sigma(x) = sigma(y) = sigma(z) = x+y+z, x

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

Offset: 1

Author

Yasutoshi Kohmoto, Dec 11 2006

Keywords

• nonn

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

Examples

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

Links

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

Crossrefs

Cf. A125491, A125492, A137231 (x+y+z).

Cf. A036471 - A036474 and A116148 (amicable quadruples).

Cf. A233553 for amicable 5-tuples.

Cf. A000203 (sigma function).

Extensions

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

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