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 A120415 Expansion of 1/(1-x-x^3-x^6). 2

%I

%S 1,1,1,2,3,4,7,11,16,25,39,59,91,141,216,332,512,787,1210,1863,2866,

%T 4408,6783,10436,16054,24700,38002,58464,89947,138385,212903,327550,

%U 503937,775304,1192801,1835123,2823330,4343681,6682741,10281375

%N Expansion of 1/(1-x-x^3-x^6).

%C Number of compositions of n into parts 1, 3, and 6. [_Joerg Arndt_, Sep 03 2013]

%H Vincenzo Librandi, <a href="/A120415/b120415.txt">Table of n, a(n) for n = 0..1000</a>

%H K. Edwards, <a href="http://www.fq.math.ca/Papers1/46_47-1/Edwards11-08.pdf">A Pascal-like triangle related to the tribonacci numbers</a>, Fib. Q., 46/47 (2008/2009), 18-25.

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,0,0,1).

%F a(n) = a(n-1) + a(n-3) + a(n-6).

%t CoefficientList[Series[1 / (1 - x - x^3 - x^6), {x, 0, 40}], x] (* _Vincenzo Librandi_, Sep 03 2013 *)

%o (MAGMA) I:=[1,1,1,2,3,4]; [n le 6 select I[n] else Self(n-1)+Self(n-3)+Self(n-6): n in [1..40]]; // _Vincenzo Librandi_, Sep 03 2013

%K easy,nonn

%O 0,4

%A _Jon E. Schoenfield_, Aug 27 2006

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Last modified July 23 17:22 EDT 2021. Contains 346259 sequences. (Running on oeis4.)