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.

Showing 1-3 of 3 results.

A052103 The third of the three sequences associated with the polynomial x^3 - 2.

Original entry on oeis.org

0, 0, 1, 3, 6, 12, 27, 63, 144, 324, 729, 1647, 3726, 8424, 19035, 43011, 97200, 219672, 496449, 1121931, 2535462, 5729940, 12949227, 29264247, 66134880, 149459580, 337766841, 763326423, 1725057486, 3898493712, 8810287947, 19910555163
Offset: 0

Views

Author

Ashok K. Gupta and Ashok K. Mittal (akgjkiapt(AT)hotmail.com), Jan 20 2000

Keywords

Comments

If x^3 = 2 and n >= 0, then there are unique integers a, b, c such that (1 + x)^n = a + b*x + c*x^2. The coefficient c is a(n).

Examples

			G.f. = x^2 + 3*x^3 + 6*x^4 + 12*x^5 + 27*x^6 + 63*x^7 + 144*x^8 + ...
		

References

  • Maribel Díaz Noguera [Maribel Del Carmen Díaz Noguera], Rigoberto Flores, Jose L. Ramirez, and Martha Romero Rojas, Catalan identities for generalized Fibonacci polynomials, Fib. Q., 62:2 (2024), 100-111. See Table 3.
  • R. Schoof, Catalan's Conjecture, Springer-Verlag, 2008, pp. 17-18.

Crossrefs

Programs

  • Magma
    I:=[0,0,1]; [n le 3 select I[n] else 3*(Self(n-1) -Self(n-2) +Self(n-3)): n in [1..41]]; // G. C. Greubel, Apr 15 2021
    
  • Maple
    A052103:= n-> add(2^j*binomial(n, 3*j+2), j = 0..floor(1/3*n));
    seq(A052103(n), n = 0..40); # G. C. Greubel, Apr 15 2021
  • Mathematica
    LinearRecurrence[{3,-3,3}, {0,0,1}, 32] (* Ray Chandler, Sep 23 2015 *)
  • PARI
    {a(n) = polcoeff( lift( Mod(1 + x, x^3 - 2)^n ), 2)} /* Michael Somos, Aug 05 2009 */
    
  • PARI
    {a(n) = sum(k=0, n\3, 2^k * binomial(n, 3*k + 2))} /* Michael Somos, Aug 05 2009 */
    
  • PARI
    {a(n) = if( n<0, 0, polcoeff( x^2 / (1 - 3*x + 3*x^2 - 3*x^3) + x * O(x^n), n))} /* Michael Somos, Aug 05 2009 */
    
  • Sage
    [sum(2^j*binomial(n, 3*j+2) for j in (0..n//3)) for n in (0..40)] # G. C. Greubel, Apr 15 2021

Formula

a(n) = 3*a(n-1) - 3*a(n-2) + 3*a(n-3), n > 2.
a(n) = Sum_{0..floor(n/3)}, 2^k * binomial(n, 3*k+2). - Ralf Stephan, Aug 30 2004
From Paul Curtz, Mar 10 2008: (Start)
a(n) = 4*a(n-1) - 6*a(n-2) + 6*a(n-3) - 3*a(n-4).
a(n) is binomial transform of 0, 0, 1, 0, 0, 2, 0, 0, 4, 0, 0, 8, 0, 0, 16, 0, 0, 32 (see A077958).
a(n) is a sequence identical to half its third differences. (End)
From R. J. Mathar, Apr 01 2008: (Start)
O.g.f.: x^2/(1 - 3*x + 3*x^2 - 3*x^3).
a(n+1) - a(n) = A052102(n). (End)

Extensions

More terms from R. J. Mathar, Apr 01 2008

A077959 Expansion of 1/(1+2*x^3).

Original entry on oeis.org

1, 0, 0, -2, 0, 0, 4, 0, 0, -8, 0, 0, 16, 0, 0, -32, 0, 0, 64, 0, 0, -128, 0, 0, 256, 0, 0, -512, 0, 0, 1024, 0, 0, -2048, 0, 0, 4096, 0, 0, -8192, 0, 0, 16384, 0, 0, -32768, 0, 0, 65536, 0, 0, -131072, 0, 0, 262144, 0, 0, -524288, 0, 0, 1048576, 0, 0, -2097152, 0, 0, 4194304, 0, 0, -8388608, 0
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2002

Keywords

Crossrefs

Cf. A077958.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 80); Coefficients(R!( 1/(1+2*x^3) )); // G. C. Greubel, Jun 23 2019
    
  • Mathematica
    CoefficientList[Series[1/(1+2x^3),{x,0,80}],x] (* or *) LinearRecurrence[ {0,0,-2},{1,0,0},80] (* Harvey P. Dale, Dec 19 2012 *)
  • PARI
    Vec(1/(1+2*x^3)+O(x^80)) \\ Charles R Greathouse IV, Sep 27 2012
    
  • Sage
    (1/(1+2*x^3)).series(x, 80).coefficients(x, sparse=False) # G. C. Greubel, Jun 23 2019

Formula

a(0)=1, a(1)=0, a(2)=0, a(n) = -2*a(n-3). - Harvey P. Dale, Dec 19 2012
a(n) = (-1)^n * A077958(n). - R. J. Mathar, Mar 04 2018

A078029 Expansion of (1-x)/(1-2*x^3).

Original entry on oeis.org

1, -1, 0, 2, -2, 0, 4, -4, 0, 8, -8, 0, 16, -16, 0, 32, -32, 0, 64, -64, 0, 128, -128, 0, 256, -256, 0, 512, -512, 0, 1024, -1024, 0, 2048, -2048, 0, 4096, -4096, 0, 8192, -8192, 0, 16384, -16384, 0, 32768, -32768, 0, 65536, -65536, 0, 131072, -131072, 0, 262144, -262144, 0, 524288, -524288, 0
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2002

Keywords

Programs

  • GAP
    a:=[1,-1,0];; for n in [4..60] do a[n]:=2*a[n-3]; od; a; # G. C. Greubel, Aug 05 2019
  • Magma
    &cat[[2^n, -2^n, 0]: n in [0..60]]; // Vincenzo Librandi, May 10 2015
    
  • Maple
    seq(op([2^n,-2^n,0]), n=0..60); # Robert Israel, May 11 2015
  • Mathematica
    CoefficientList[Series[(1-x)/(1-2*x^3), {x, 0, 60}], x] (* Vincenzo Librandi, May 10 2015 *)
  • PARI
    my(x='x+O('x^60)); Vec((1-x)/(1-2*x^3)) \\ G. C. Greubel, Aug 05 2019
    
  • Sage
    ((1-x)/(1-2*x^3)).series(x, 60).coefficients(x, sparse=False) # G. C. Greubel, Aug 05 2019
    

Formula

G.f.: (1-x)/(1-2*x^3).
a(n) = (-1)^floor(4n/3)*(2-2*0^mod(n+1,3))^floor((n+1)/3). - Wesley Ivan Hurt, May 09 2015
a(n) = A077958(n) - A077958(n-1). - R. J. Mathar, Mar 04 2018
a(n) = (4^(n/6)/6)*(2 - 2^(2/3) + 2^(5/3)*sin(Pi*(2*n/3 + 5/6)) - 4*sin(Pi*(2*n/3 + 3/2))). - Eric Simon Jacob, Jul 14 2024
Showing 1-3 of 3 results.