A273936 Amicable 5-tuples: (x1,...,x5) such that sigma(x1)=...=sigma(x5)=x1+...+x5, x1<x2<x3<x4<x5. Sequence gives sigma numbers.

294821130240, 350100092160, 368526412800, 457350727680, 457350727680, 466800122880, 466800122880, 466800122880, 522686545920

Offset

1,1

Comments

The 5-tuple starting with 53542288800 was given by Donovan Johnson. The common value of sigma(x) is 294821130240.

A larger 5-tuple, (55766707476480, 56992185169920, 57515254917120, 57754372515840, 57829096765440), was found by Michel Marcus on Dec 09 2013. The common value of sigma(x) is 285857616844800.

A still larger example (227491164588441600, 228507506351308800, 229862628701798400, 230878970464665600, 243752632794316800), probably the first one to be published, had been found by Yasutoshi Kohmoto in 2008, cf. link to SeqFan post.

Other terms from John Cerkan.

There are different definitions for amicable k-tuples, cf. link to MathWorld.

Links

Table of n, a(n) for n=1..9.

John Cerkan, More terms, with gaps.

Yasutoshi Kohmoto, Sigma(x)=Sigma(y)=Sigma(z)=Sigma(u)=Sigma(v)=x+y+z+u+v, SeqFan list, Nov 23 2008

Yasutoshi Kohmoto, Sigma(x)=Sigma(y)=Sigma(z)=Sigma(u)=Sigma(v)=x+y+z+u+v, SeqFan list, Dec 09 2013

Eric W. Weisstein, Amicable Triple. From MathWorld--A Wolfram Web Resource.

Crossrefs

Cf. A233553, A273928, A273930, A273931, A273933, A273934 (5-tuples).

Cf. A036471 - A036474 and A116148 (quadruples).

Cf. A125490 - A125492 and A137231 (triples).

Sequence in context: A017663 A345864 A354070 * A287247 A172578 A172588

Adjacent sequences: A273933 A273934 A273935 * A273937 A273938 A273939

Keyword

nonn,more

Author

John Cerkan, Jun 04 2016

Status

approved