A017878 Expansion of 1/(1-x^9-x^10-x^11).

1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 2, 3, 2, 1, 0, 0, 0, 0, 1, 3, 6, 7, 6, 3, 1, 0, 0, 1, 4, 10, 16, 19, 16, 10, 4, 1, 1, 5, 15, 30, 45, 51, 45, 30, 15, 6, 7, 21, 50, 90, 126, 141, 126, 90, 51, 28, 34, 78, 161

Offset

0,20

Comments

Number of compositions (ordered partitions) of n into parts 9, 10 and 11. - Ilya Gutkovskiy, May 27 2017

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

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

Formula

a(n) = a(n-9) +a(n-10) +a(n-11) for n>10. - Vincenzo Librandi, Jul 01 2013

Mathematica

CoefficientList[Series[1 / (1 - Total[x^Range[9, 11]]), {x, 0, 80}], x] (* Vincenzo Librandi, Jul 01 2013 *)
LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1}, {1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1}, 70] (* Harvey P. Dale, May 25 2023 *)

Prog

(Magma) m:=70; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^9-x^10-x^11))); /* or */ I:=[1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1]; [n le 11 select I[n] else Self(n-9)+Self(n-10)+Self(n-11): n in [1..70]]; // Vincenzo Librandi, Jul 01 2013

Crossrefs

Sequence in context: A202815 A049336 A017888 * A301572 A017868 A353158

Adjacent sequences: A017875 A017876 A017877 * A017879 A017880 A017881

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved