OFFSET
0,3
COMMENTS
Number of compositions (ordered partitions) of n into elements of the set {1,2,5,6}.
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.
Milan Janjic, Binomial Coefficients and Enumeration of Restricted Words, Journal of Integer Sequences, 2016, Vol 19, #16.7.3.
Index entries for linear recurrences with constant coefficients, signature (1,1,0,0,1,1).
FORMULA
a(n) = a(n-1) + a(n-2) + a(n-5) + a(n-6).
G.f.: -1/(x^6 + x^5 + x^2 + x - 1).
MAPLE
g:=1/(1-z-z^2-z^5-z^6): gser:=series(g, z=0, 49): seq((coeff(gser, z, n)), n=0..35); # Zerinvary Lajos, Apr 17 2009
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladimir Baltic, Feb 19 2003
STATUS
approved