OFFSET
0,12
COMMENTS
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,-1,0,1}.
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.
LINKS
Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (2010), 119-135.
Index entries for linear recurrences with constant coefficients, signature (0,1,0,0,2,3,-1,-3,1,-1,-1,-3,1,3,-2,0,0,1,0,-1).
FORMULA
Recurrence: a(n) = a(n-2)+2*a(n-5)+3*a(n-6)-a(n-7)-3*a(n-8)+a(n-9)-a(n-10)-a(n-11)-3*a(n-12)+a(n-13)+3*a(n-14)-2*a(n-15)+a(n-18)-a(n-20).
G.f.: -(x^14-x^12+x^9-2*x^8+2*x^6+x^5+x^2-1)/(x^20-x^18+2*x^15-3*x^14-x^13+3*x^12+x^11+x^10-x^9+3*x^8+x^7-3*x^6-2*x^5-x^2+1).
MATHEMATICA
LinearRecurrence[{0, 1, 0, 0, 2, 3, -1, -3, 1, -1, -1, -3, 1, 3, -2, 0, 0, 1, 0, -1}, {1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 4, 1, 1, 1, 1, 10, 10, 7, 7}, 60] (* Harvey P. Dale, Dec 19 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladimir Baltic, Feb 17 2003
STATUS
approved