|
Search: id:A116219
|
|
|
| A116219 |
|
If X_1,...,X_n is a partition of a 3n-set X into 3-blocks then a(n) is equal to the number of permutations f of X such that f( X_i)<>X_i, (i=1,...n). |
|
+0
1
|
|
| 0, 684, 350352, 470444112, 1293433432704, 6355554535465920, 50823027472983319296, 618002474327361540442368, 10855431334634213344062394368, 264600531449039456516679858441216
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
|
|
FORMULA
|
a(n)=sum((-6)^i*binomial(n,i)*(3*n-3*i)!,i=0..n).
|
|
EXAMPLE
|
a(5)=1293433432704
|
|
MAPLE
|
a:=n->sum((-6)^i*binomial(n, i)*(3*n-3*i)!, i=0..n).
|
|
CROSSREFS
|
Cf. A116218, A116220, A116221, A127888.
Sequence in context: A015386 A022050 A107514 this_sequence A101944 A045150 A057116
Adjacent sequences: A116216 A116217 A116218 this_sequence A116220 A116221 A116222
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Milan R. Janjic (agnus(AT)blic.net), Apr 09 2007
|
|
|
Search completed in 0.002 seconds
|
