|
Search: id:A111279
|
|
|
| A111279 |
|
Number of permutations avoiding the patterns {3241,3421,4321}; number of weak sorting class based on 3241. |
|
+0
2
|
|
| 1, 2, 6, 21, 79, 309, 1237, 5026, 20626, 85242, 354080, 1476368, 6173634, 25873744, 108628550, 456710589, 1922354351, 8098984433, 34147706833, 144068881455, 608151037123, 2568318694867, 10850577045131, 45856273670841
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Is this the same sequence as A026737? - Andrew Plewe, May 09 2007
|
|
REFERENCES
|
M. Albert, R. Aldred, M. Atkinson, C Handley, D. Holton, D. McCaughan and H. van Ditmarsch, Sorting Classes, Elec. J. of Comb. 12 (2005)
|
|
FORMULA
|
O.g.f.: (3-13*x+2*x^2+(5*x-1)*sqrt(1-4*x))/(2*(1-4*x-x^2)).
|
|
MATHEMATICA
|
Rest[ CoefficientList[ Series[(3 - 13x + 2x^2 + (5x - 1)*Sqrt[1 - 4x])/(2*(1 - 4x - x^2)), {x, 0, 24}], x]] (* Robert G. Wilson v *)
|
|
CROSSREFS
|
Sequence in context: A150196 A148491 A026737 this_sequence A150197 A150198 A033321
Adjacent sequences: A111276 A111277 A111278 this_sequence A111280 A111281 A111282
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Len Smiley ( smiley (at) math.uaa.alaska.edu ), Nov 01 2005
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(at)rgwv.com), Nov 04 2005
|
|
|
Search completed in 0.002 seconds
|
