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 A222975 Smallest member of sociable quadruples with signature: abundant, abundant, deficient, deficient. 3

%I

%S 1264460,2115324,2784580,7169104,18656380,28158165,81128632,174277820,

%T 498215416,1236402232,1799281330,2387776550,2717495235,2879697304,

%U 15837081520,17616303220,91411869465,111375706442,661126361272,741158497112

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

%C 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).

%H J. M. Pedersen, <a href="http://amicable.homepage.dk/knwnc4.htm">Known Sociable Numbers of order four</a>

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

%Y Cf. A090615, A222976, A222977, A222978.

%K nonn

%O 1,1

%A _Michel Marcus_, Mar 11 2013

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Last modified December 3 20:26 EST 2022. Contains 358543 sequences. (Running on oeis4.)