|
Search: id:A080014
|
|
|
| A080014 |
|
Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=2, r=2, I={1}. |
|
+0
60
|
|
| 1, 1, 1, 3, 6, 10, 18, 35, 65, 119, 221, 412, 764, 1416, 2629, 4881, 9057, 16807, 31194, 57894, 107442, 199399, 370065, 686799, 1274617, 2365544, 4390184, 8147680, 15121161, 28063153, 52082017, 96658283, 179386750, 332921362, 617864098
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
REFERENCES
|
D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial theory and its applications, II (Proc. Colloq., Balatonfured, 1969), pp. 755-770. North-Holland, Amsterdam, 1970.
|
|
FORMULA
|
Recurrence: a(n) = a(n-1)+a(n-2)+a(n-3)+a(n-4)-a(n-5)-a(n-6) G.f.: -(x^2-1)/(x^6+x^5-x^4-x^3-x^2-x+1)
|
|
CROSSREFS
|
Cf. A002524..A002529, A072827, A072850..A072856, A079955..A080014.
Sequence in context: A076251 A029864 A075111 this_sequence A132274 A091714 A017991
Adjacent sequences: A080011 A080012 A080013 this_sequence A080015 A080016 A080017
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladimir Baltic (baltic(AT)galeb.etf.bg.ac.yu), Jan 24 2003
|
|
|
Search completed in 0.002 seconds
|
