A123943 The (1,5)-entry in the 5 X 5 matrix M^n, where M={{5, 3, 2, 1, 1}, {3, 2, 1, 1, 0}, {2, 1, 1, 0, 0}, {1, 1, 0, 0, 0}, {1, 0, 0, 0, 0}}.
0, 1, 5, 40, 315, 2490, 19681, 155563, 1229604, 9719061, 76821600, 607214857, 4799560053, 37936780428, 299860673343, 2370164848026, 18734305316497, 148080078051971, 1170457572108040, 9251554605638681, 73126326541645648, 578006601205833441
Offset: 0
References
- See A123942 for references.
Links
- Colin Barker, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (8,0,-6,0,1).
Programs
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GAP
a:=[0,1,5,40,315];; for n in [6..30] do a[n]:=8*a[n-1]-6*a[n-3] +a[n-5]; od; a; # G. C. Greubel, Aug 05 2019
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Magma
R
:=PowerSeriesRing(Integers(), 30); [0] cat Coefficients(R!( x*(1-3*x+x^3)/(1-8*x+6*x^3-x^5) )); // G. C. Greubel, Aug 05 2019 -
Maple
with(linalg): M[1]:=matrix(5,5,[5,3,2,1,1,3,2,1,1,0,2,1,1,0,0,1,1,0,0,0,1,0,0,0,0]): for n from 2 to 30 do M[n]:=multiply(M[1],M[n-1]) od: 0,seq(M[n][1,5],n=1..30); a[0]:=0: a[1]:=1: a[2]:=5: a[3]:=40: a[4]:=315: for n from 5 to 30 do a[n]:=8*a[n-1]-6*a[n-3]+a[n-5] od: seq(a[n],n=0..30); # third Maple program: a:= n-> (<<0|1|0|0|0>, <0|0|1|0|0>, <0|0|0|1|0>, <0|0|0|0|1>, <1|0|-6|0|8>>^n. <<0, 1, 5, 40, 315>>)[1, 1]: seq(a(n), n=0..30); # Alois P. Heinz, Aug 05 2019 -
Mathematica
M = {{5,3,2,1,1}, {3,2,1,1,0}, {2,1,1,0,0}, {1,1,0,0,0}, {1,0,0,0,0}}; v[1] = {0,0,0,0,1}; v[n_]:= v[n] = M.v[n-1]; Table[v[n][[1]], {n, 30}] LinearRecurrence[{8,0,-6,0,1}, {0,1,5,40,315}, 30] (* G. C. Greubel, Aug 05 2019 *) -
PARI
concat(0, Vec(x*(1-3*x+x^3)/(1-8*x+6*x^3-x^5) + O(x^30))) \\ Colin Barker, Mar 03 2017
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Sage
(x*(1-3*x+x^3)/(1-8*x+6*x^3-x^5)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Aug 05 2019
Formula
a(n) = 8*a(n-1) - 6*a(n-3) + a(n-5) for n>=5 (follows from the minimal polynomial of the matrix M).
G.f.: x*(1 - 3*x + x^3) / (1 - 8*x + 6*x^3 - x^5). - Colin Barker, Mar 03 2017
Extensions
Edited by N. J. A. Sloane, Dec 04 2006