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A017847 Expansion of 1/(1-x^6-x^7). 4
1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 1, 3, 3, 1, 0, 0, 1, 4, 6, 4, 1, 0, 1, 5, 10, 10, 5, 1, 1, 6, 15, 20, 15, 6, 2, 7, 21, 35, 35, 21, 8, 9, 28, 56, 70, 56, 29, 17, 37, 84, 126, 126, 85, 46, 54, 121, 210, 252, 211 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,14

COMMENTS

Number of compositions of n into parts 6 and 7. [Joerg Arndt, Jun 27 2013]

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 1, 1).

FORMULA

a(0)=1, a(1)=0,a(2)=0, a(3)=0, a(4)=0, a(5)=0, a(6)=1; for n>6, a(n) = a(n-6)+a(n-7). - Harvey P. Dale, Dec 15 2012

MATHEMATICA

CoefficientList[Series[1/(1-x^6-x^7), {x, 0, 70}], x] (* or *)  LinearRecurrence[{0, 0, 0, 0, 0, 1, 1}, {1, 0, 0, 0, 0, 0, 1}, 70] (* Harvey P. Dale, Dec 15 2012 *)

CoefficientList[Series[1 / (1 - Total[x^Range[6, 7]]), {x, 0, 70}], x] (* Vincenzo Librandi, Jun 27 2013 *)

PROG

(MAGMA) m:=70; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^6-x^7))); /* or */ I:=[1, 0, 0, 0, 0, 0, 1]; [n le 7 select I[n] else Self(n-6)+Self(n-7): n in [1..70]]; // Vincenzo Librandi, Jun 27 2013

CROSSREFS

Sequence in context: A186084 A301345 A047998 * A127841 A091006 A167365

Adjacent sequences:  A017844 A017845 A017846 * A017848 A017849 A017850

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified July 23 13:58 EDT 2019. Contains 325254 sequences. (Running on oeis4.)