|
Search: id:A046718
|
|
|
| A046718 |
|
Number of permutations of [ n ] with exactly 1 132-pattern and 2 123-patterns. |
|
+0
1
|
|
| 1, 4, 14, 47, 152, 472, 1408, 11264, 30464, 80384, 207616, 526336, 1312768, 3227648, 7835648, 18808832, 44695552, 105250816, 245825536, 569901056, 1312292864, 3003121664, 6833569792
(list; graph; listen)
|
|
|
OFFSET
|
4,2
|
|
|
REFERENCES
|
The Number of Permutations With a Prescribed Number of 132 and 123 Patterns, S.Ekhad, A.Robertson, D.Zeilberger, preprint
|
|
LINKS
|
link to preprint
|
|
FORMULA
|
G.f.: -x^4*(x^3-6*x^2+4*x-1)/(1-2*x)^2
|
|
EXAMPLE
|
a(5)=4: [ 12345 ]->[ 24351 ], [ 24315 ], [ 51324 ], or [ 41325 ]
|
|
CROSSREFS
|
Cf. A001815, A001787, A011782, A001793.
Sequence in context: A124805 A121530 A121299 this_sequence A104487 A094789 A082574
Adjacent sequences: A046715 A046716 A046717 this_sequence A046719 A046720 A046721
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Len Smiley (smiley(AT)math.uaa.alaska.edu)
|
|
|
Search completed in 0.002 seconds
|
