cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A073313 Binomial transform of generalized Lucas numbers S(n) = S(n-1) + S(n-2) + S(n-3), S(0)=3, S(1)=1, S(2)=3.

Original entry on oeis.org

3, 4, 8, 22, 64, 184, 524, 1488, 4224, 11992, 34048, 96672, 274480, 779328, 2212736, 6282592, 17838080, 50647424, 143802560, 408296704, 1159271424, 3291504000, 9345523712, 26534621696, 75339399936, 213910160384, 607352285184
Offset: 0

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Author

Mario Catalani (mario.catalani(AT)unito.it), Jul 26 2002

Keywords

Comments

Limit as n-> infinity of a(n)/a(n-1) is 1+c, where c = 1.83928675...

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, San Diego, 1995.

Crossrefs

Cf. A001644.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (3-8*x+4*x^2)/(1-4*x+4*x^2-2*x^3) )); // G. C. Greubel, Apr 22 2019
    
  • Mathematica
    f[n_]:= f[n]=4*f[n-1]-4*f[n-2]+2*f[n-3]; f[0]=3; f[1]=4; f[2]=8; Table[f[n], {n, 0, 30}]
    LinearRecurrence[{4,-4,2},{3,4,8},30] (* Harvey P. Dale, May 08 2015 *)
  • PARI
    my(x='x+O('x^30)); Vec((3-8*x+4*x^2)/(1-4*x+4*x^2-2*x^3)) \\ G. C. Greubel, Apr 22 2019
    
  • Sage
    ((3-8*x+4*x^2)/(1-4*x+4*x^2-2*x^3)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Apr 22 2019

Formula

a(n) is the trace of the n-th power of 3 X 3 matrix: first row (2, 1, 0), second row (1, 1, 1), third row (1, 0, 1). It satisfies recurrence a(n) = 4*a(n-1) - 4*a(n-2) + 2*a(n-3), a(0)=3, a(1)=4, a(2)=8.
G.f.: (3 - 8*x + 4*x^2)/(1 - 4*x + 4*x^2 - 2*x^3).