

A090615


Smallest member of sociable quadruples.


8



1264460, 2115324, 2784580, 4938136, 7169104, 18048976, 18656380, 28158165, 46722700, 81128632, 174277820, 209524210, 330003580, 498215416, 1236402232, 1799281330, 2387776550, 2717495235, 2879697304, 3705771825, 4424606020
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OFFSET

1,1


COMMENTS

120 sociable numbers of order 4 are known as of Feb. 2003.
142 were known in 2007 (http://amicable.homepage.dk/knwnc4.htm).
201 are known in 2012.
210 were known in April 2013.  Michel Marcus, Nov 10 2013


REFERENCES

R. K. Guy and J. L. Selfridge, Interim report on aliquot series, pp. 557580 of Proceedings Manitoba Conference on Numerical Mathematics. University of Manitoba, Winnipeg, Oct 1971.


LINKS

Table of n, a(n) for n=1..21.
K. Blankenagel, W. Borho, A vom Stein, New amicable fourcycles, Math Comp 72 (2003) vol. 244, 2071.
D. Moews, A list of aliquot cycles of length greater than 2.
Eric Weisstein's World of Mathematics, Sociable Numbers


CROSSREFS

Cf. A003023, A003416, A052470.
Sequence in context: A250825 A292217 A072892 * A222975 A180624 A081430
Adjacent sequences: A090612 A090613 A090614 * A090616 A090617 A090618


KEYWORD

nonn


AUTHOR

Eric W. Weisstein, Dec 06 2003


STATUS

approved



