This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A222975 #12 Apr 05 2024 08:17:20 %S A222975 1264460,2115324,2784580,7169104,18656380,28158165,81128632,174277820, %T A222975 498215416,1236402232,1799281330,2387776550,2717495235,2879697304, %U A222975 15837081520,17616303220,91411869465,111375706442,661126361272,741158497112,1045805730255,1092162882824 %N A222975 Smallest member of sociable quadruples with signature: abundant, abundant, deficient, deficient. %C A222975 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 A222975 Amiram Eldar, <a href="/A222975/b222975.txt">Table of n, a(n) for n = 1..28</a> %H A222975 Jan Munch Pedersen, <a href="http://62.198.248.44/aliquot/knwnc4.htm">Known Sociable Numbers of order four</a>, Tables of Aliquot Cycles. %e A222975 The first quadruple of this type is: 1264460, 1547860, 1727636, 1305184, that are respectively abundant, abundant, deficient, deficient. %Y A222975 Cf. A090615, A222976, A222977, A222978. %K A222975 nonn %O A222975 1,1 %A A222975 _Michel Marcus_, Mar 11 2013 %E A222975 a(21)-a(22) from _Amiram Eldar_, Apr 05 2024