A079959 Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=1, r=5, I={2,4}.

1, 1, 2, 3, 6, 10, 19, 33, 60, 106, 191, 340, 610, 1089, 1950, 3485, 6236, 11150, 19946, 35670, 63802, 114107, 204091, 365018, 652857, 1167652, 2088402, 3735179, 6680529, 11948378, 21370166, 38221375, 68360472, 122265404, 218676571

Offset: 0

Author

Vladimir Baltic, Feb 19 2003

Keywords

• nonn
• easy

Comments

Number of compositions (ordered partitions) of n into elements of the set {1,2,4,6}.

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 (1,1,0,1,0,1).

Crossrefs

Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.

Formula

a(n) = a(n-1)+a(n-2)+a(n-4)+a(n-6).

G.f.: -1/(x^6+x^4+x^2+x-1).