login
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
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
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. A319902 (where the terms are entered by increasing value).
Sequence in context: A237778 A123138 A319902 * A095974 A022202 A118062
KEYWORD
nonn,tabf,more
AUTHOR
Labos Elemer, Sep 02 2004
EXTENSIONS
More terms from Michel Marcus, Oct 05 2018
STATUS
approved