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.

263820, 263940, 280380, 280500, 395730, 395910, 420570, 420750, 172459210, 218725430, 272130250, 218628662, 209524210, 246667790, 231439570, 230143790, 384121920, 384296640, 408233280, 408408000

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