|
|
A116786
|
|
Number of permutations of length n which avoid the patterns 2314, 2431, 4123.
|
|
0
|
|
|
1, 2, 6, 21, 72, 228, 670, 1864, 5000, 13099, 33789, 86239, 218432, 550107, 1379348, 3446817, 8590103, 21362792, 53037845, 131501095, 325690131, 805941635, 1992965105, 4925514322, 12167639830, 30047049122, 74176872249, 183075826494
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
G.f.: A(x) = -{6x^6-22x^5+35x^4-36x^3+22x^2-7x+1)x}/{(2x-1)(3x^3-5x^2+4x-1)(x-1)^3}
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|