|
Search: id:A079995
|
|
|
| A079995 |
|
Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=3, r=3, I={2}. |
|
+0
1
|
|
| 1, 1, 2, 4, 14, 39, 103, 255, 665, 1741, 4605, 12046, 31474, 82206, 215157, 563083, 1473635, 3855111, 10085589, 26386595, 69038554, 180630858, 472594580, 1236463719, 3235013481, 8463923170, 22144596592, 57937977232, 151585883920
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
COMMENT
|
Also, number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=3, r=3, I={-2}.
|
|
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)+2*a(n-2)+3*a(n-3)+4*a(n-4)+6*a(n-5)+13*a(n-6)-9*a(n-7)-11*a(n-8)-7*a(n-9)+5*a(n-10)-a(n-11)-11*a(n-12)+3*a(n-13)+9*a(n-14)+4*a(n-15)-4*a(n-16)-a(n-17)+2*a(n-18)-a(n-19)-a(n-20) G.f.: -(x^14-x^12+x^11-x^10-x^9-x^8+3*x^6-x^5+x^4+3*x^3+x^2-1)/(x^20+x^19-2*x^18+x^17+4*x^16-4*x^15-9*x^14-3*x^13+11*x^12+x^11-5*x^10+7*x^9+11*x^8+9*x^7-13*x^6-6*x^5-4*x^4-3*x^3-2*x^2-x+1)
|
|
CROSSREFS
|
Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A035010 A055540 A006252 this_sequence A152011 A000912 A128750
Adjacent sequences: A079992 A079993 A079994 this_sequence A079996 A079997 A079998
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladimir Baltic (baltic(AT)matf.bg.ac.yu), Feb 17 2003
|
|
|
Search completed in 0.002 seconds
|
