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A098188 Irregular triangle with 4 columns which contains in each row the members of a 4-cycle under the map x->A063919(x), iteration of summing the proper-unitary divisors. 2
263820, 263940, 280380, 280500, 395730, 395910, 420570, 420750, 172459210, 218725430, 272130250, 218628662, 209524210, 246667790, 231439570, 230143790, 384121920, 384296640, 408233280, 408408000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Initial values attracted by this sequence are in A098187.

The iteration of this function also contains 2-cycles like 114->126->114... or 1140 -> 1260 ->1140,... or 3-cycles like 30->42->54->30->....

LINKS

Table of n, a(n) for n=1..20.

J. O. M. Pedersen, Known Unitary Sociable Numbers of order four [Via Internet Archive Wayback-Machine]

J. O. M. Pedersen, Order 4 cycles, 2007.

Eric Weisstein's World of Mathematics, Unitary Sociable Numbers

EXAMPLE

The first line represents the 4-cycle  280500->263820->263940->280380->280500->...,

The second line represents the 4-cycle 420750->395730->395910->420570->420750->..

CROSSREFS

Cf. A098185, A098186, A002827, A097024, A097030, A098187.

Cf. A319902 (where the terms are entered by increasing value).

Sequence in context: A237778 A123138 A319902 * A095974 A022202 A118062

Adjacent sequences:  A098185 A098186 A098187 * A098189 A098190 A098191

KEYWORD

nonn,tabf,more

AUTHOR

Labos Elemer, Sep 02 2004

EXTENSIONS

More terms from Michel Marcus, Oct 05 2018

STATUS

approved

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Last modified April 25 16:08 EDT 2019. Contains 322461 sequences. (Running on oeis4.)