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A079955 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={0,2,3}. 77
1, 0, 1, 0, 1, 1, 2, 2, 3, 3, 5, 6, 9, 11, 15, 19, 26, 34, 46, 60, 80, 105, 140, 185, 246, 325, 431, 570, 756, 1001, 1327, 1757, 2328, 3083, 4085, 5411, 7169, 9496, 12580, 16664, 22076, 29244, 38741, 51320, 67985, 90060, 119305, 158045, 209366, 277350, 367411 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

COMMENTS

Number of compositions (ordered partitions) of n into elements of the set {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

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

FORMULA

a(n) = a(n-2) + a(n-5) + a(n-6).

G.f.: 1/(1 - x^2 - x^5 - x^6).

MAPLE

seq(coeff(series(1/(1-x^2-x^5-x^6), x, n+1), x, n), n = 0..50); # G. C. Greubel, Dec 11 2019

MATHEMATICA

LinearRecurrence[{0, 1, 0, 0, 1, 1}, {1, 0, 1, 0, 1, 1}, 51] (* Jean-François Alcover, Dec 11 2019 *)

PROG

(PARI) a(n) = ([0, 1, 0, 0, 0, 0; 0, 0, 1, 0, 0, 0; 0, 0, 0, 1, 0, 0; 0, 0, 0, 0, 1, 0; 0, 0, 0, 0, 0, 1; 1, 1, 0, 0, 1, 0]^n*[1; 0; 1; 0; 1; 1])[1, 1] \\ Charles R Greathouse IV, Jul 28 2015

(MAGMA) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1-x^2-x^5-x^6) )); // G. C. Greubel, Dec 11 2019

(Sage)

def A079955_list(prec):

    P.<x> = PowerSeriesRing(ZZ, prec)

    return P( 1/(1-x^2-x^5-x^6) ).list()

A079955_list(50) # G. C. Greubel, Dec 11 2019

CROSSREFS

Cf. A002524, A002525, A002526, A002527, A002528, A002529, A072827.

Cf. A072850, A072851, A072852, A072853, A072854, A072855, A072856.

Cf. A079955 - A080014.

Sequence in context: A274158 A020999 A309712 * A192928 A136417 A322787

Adjacent sequences:  A079952 A079953 A079954 * A079956 A079957 A079958

KEYWORD

nonn,easy

AUTHOR

Vladimir Baltic, Feb 19 2003

STATUS

approved

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Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)