A173855 a(n) = A173039(n+4) - A173039(n+1).
8, 4, 24, 40, 12, 56, 72, 20, 88, 104, 28, 120, 136, 36, 152, 168, 44, 184, 200, 52, 216, 232, 60, 248, 264, 68, 280, 296, 76, 312, 328, 84, 344, 360, 92, 376, 392, 100, 408, 424, 108, 440, 456, 116, 472, 488, 124, 504, 520, 132, 536, 552, 140, 568, 584, 148
Offset: 1
Examples
a(1) = 5 - (-3) = 8, a(2) = 3 - (-1) = 4, a(3) = 21 - (-3) = 24.
Links
- G. C. Greubel, Table of n, a(n) for n = 1..5000
- Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).
Programs
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Magma
m:=50; R
:=PowerSeriesRing(Integers(), m); Coefficients(R!(4*x*(x+1)*(2*x^4-x^3+7*x^2-x+2)/((x-1)^2*(x^2+x+1)^2))); // G. C. Greubel, Sep 20 2018 -
Maple
a:= LREtools[REtoproc](f(n) = 2*f(n-3)-f(n-6), f(n), zip((s,t)->f(s)=t, [$1..6],[8,4,24,40,12,56]),remember): seq(a(n), n=1..100); # Robert Israel, Oct 15 2014
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Mathematica
Rest[CoefficientList[Series[4*x*(x+1)*(2*x^4-x^3+7*x^2-x+2)/((x-1)^2*(x^2 +x+1)^2), {x, 0, 50}], x]] (* G. C. Greubel, Sep 20 2018 *) -
PARI
Vec(4*x*(x+1)*(2*x^4-x^3+7*x^2-x+2)/((x-1)^2*(x^2+x+1)^2) + O(x^100)) \\ Colin Barker, Oct 15 2014
Formula
a(n) = 4*A173773(n).
a(n) = 2*a(n-3) - a(n-6). - Colin Barker, Oct 15 2014
G.f.: 4*x*(x+1)*(2*x^4 - x^3 + 7*x^2 - x + 2) / ((x-1)^2*(x^2 + x + 1)^2). - Colin Barker, Oct 15 2014
Extensions
More terms from Colin Barker, Oct 15 2014
Comments