|
|
A274847
|
|
a(n) = number of similarity classes of groups with exactly n subgroups (see reference for precise definition of similarity classes).
|
|
2
|
|
|
1, 1, 1, 2, 2, 5, 1, 7, 2, 12, 4, 11, 1, 17, 8, 22, 3, 22, 5
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,4
|
|
COMMENTS
|
See Slatterly references for precise definition of similarity classes and a proof of the first 12 terms.
See Betz and Nash for correction of a(10) and proof of terms 13-19.
|
|
LINKS
|
|
|
EXAMPLE
|
For n = 6 the a(6) = 5 similarity classes of groups with 6 subgroups are Z_{p^5}, Z_p X Z_{q^2}, Z_3 X Z_3, S_3, Q_8.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Correction of a(10) and extension to 19 terms by David A. Nash, Jun 29 2020
|
|
STATUS
|
approved
|
|
|
|