

A222975


Smallest member of sociable quadruples with signature: abundant, abundant, deficient, deficient.


3



1264460, 2115324, 2784580, 7169104, 18656380, 28158165, 81128632, 174277820, 498215416, 1236402232, 1799281330, 2387776550, 2717495235, 2879697304, 15837081520, 17616303220, 91411869465, 111375706442, 661126361272, 741158497112
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OFFSET

1,1


COMMENTS

Members of a sociable quadruple are usually listed in the order with which they appear in the corresponding aliquot sequence. Therefore, in a sociable quadruple the 1st member is abundant, and the 4th member is deficient. In all, we can get 4 possibilities, and a sociable quadruple can be (with A for abundant, and D for deficient) : AADD, ADDD, ADAD, AAAD. The numbers in these sequences have been voluntarily limited to 12 digits maximum, the current status of the exhaustive search (see Pedersen link).


LINKS

Table of n, a(n) for n=1..20.
J. M. Pedersen, Known Sociable Numbers of order four


EXAMPLE

The first quadruple of this type is: 1264460, 1547860, 1727636, 1305184, that are respectively abundant, abundant, deficient, deficient.


CROSSREFS

Cf. A090615, A222976, A222977, A222978.
Sequence in context: A292217 A072892 A090615 * A180624 A081430 A254026
Adjacent sequences: A222972 A222973 A222974 * A222976 A222977 A222978


KEYWORD

nonn


AUTHOR

Michel Marcus, Mar 11 2013


STATUS

approved



