|
Search: id:A056308
|
|
|
| A056308 |
|
Number of reversible strings with n beads using a maximum of six different colors. |
|
+0
4
|
|
| 6, 21, 126, 666, 3996, 23436, 140616, 840456, 5042736, 30236976, 181421856, 1088414496, 6530486976, 39182222016, 235093332096, 1410555793536, 8463334761216, 50779983373056, 304679900238336
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
A string and its reverse are considered to be equivalent. Thus aabc and cbaa are considered to be identical, but abca is a different string.
|
|
REFERENCES
|
M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.
|
|
FORMULA
|
(6^n+6^[(n+1)/2])/2.
|
|
CROSSREFS
|
Cf. A005418.
Sequence in context: A009253 A012840 A013320 this_sequence A081077 A093775 A058821
Adjacent sequences: A056305 A056306 A056307 this_sequence A056309 A056310 A056311
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Marks R. Nester (nesterm(AT)dpi.qld.gov.au)
|
|
|
Search completed in 0.002 seconds
|
