login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 (list; graph; refs; listen; history; text; internal format)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 7 14:13 EDT 2022. Contains 357271 sequences. (Running on oeis4.)