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 1-7 of 7 results.

A140495 Union of A052103, A052102 and A052101, uniqued and sorted.

Original entry on oeis.org

0, 1, 2, 3, 6, 9, 12, 15, 21, 27, 36, 45, 63, 81, 99, 144, 180, 225, 324, 405, 513, 729, 918, 1161, 1647, 2079, 2619, 3726, 4698, 5913, 8424, 10611, 13365, 19035, 23976, 30213, 43011, 54189, 68283, 97200, 122472, 154305, 219672, 276777, 348705, 496449, 625482
Offset: 0

Views

Author

Paul Curtz, Jun 28 2008

Keywords

Comments

The three sequences that are merged share the same recurrence, case p=3 in A140414.
The first differences are 1, 1, 1, 3, 3, 3, 3, 6, 6, 9, 9, 18, 18, 18, 45, 36, 45, 99, 81, 108...

Crossrefs

Programs

  • Magma
    I:=[6,9,12,15,21,27,36,45,63]; [0,1,2,3] cat [n le 9 select I[n] else 3*(Self(n-3) -Self(n-6) +Self(n-9)): n in [1..51]]; // G. C. Greubel, Apr 15 2021
    
  • Mathematica
    LinearRecurrence[{0,0,3,0,0,-3,0,0,3}, {0,1,2,3,6,9,12,15,21,27,36,45,63}, 50] (* G. C. Greubel, Apr 15 2021 *)
  • Sage
    [( x*(1+2*x+3*x^2+6*x^9+3*x^5+3*x^10+9*x^11+3*x^3+3*x^4)/(1-3*x^3+3*x^6-3*x^9) ).series(x,n+1).list()[n] for n in (0..50)] # G. C. Greubel, Apr 15 2021

Formula

G.f.: x*(1+2*x+3*x^2+6*x^9+3*x^5+3*x^10+9*x^11+3*x^3+3*x^4)/(1-3*x^3+3*x^6-3*x^9).

Extensions

Edited and extended by R. J. Mathar, Mar 02 2010

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

A052102 The second of the three sequences associated with the polynomial x^3 - 2.

Original entry on oeis.org

0, 1, 2, 3, 6, 15, 36, 81, 180, 405, 918, 2079, 4698, 10611, 23976, 54189, 122472, 276777, 625482, 1413531, 3194478, 7219287, 16315020, 36870633, 83324700, 188307261, 425559582, 961731063, 2173436226, 4911794235, 11100267216, 25085727621
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 b is a(n).

Examples

			G.f.: = x + 2*x^2 + 3*x^3 + 6*x^4 + 15*x^5 + 36*x^6 + 81*x^7 + 180*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
    [n le 3 select n-1 else 3*(Self(n-1) -Self(n-2) +Self(n-3)): n in [1..40]]; // G. C. Greubel, Apr 15 2021
    
  • Maple
    A052102:= n-> add(2^j*binomial(n, 3*j+1), j=0..floor(n/3)); seq(A052102(n), n=0..40); # G. C. Greubel, Apr 15 2021
  • Mathematica
    LinearRecurrence[{3,-3,3}, {0,1,2}, 32] (* Ray Chandler, Sep 23 2015 *)
  • PARI
    {a(n) = polcoeff( lift( Mod(1 + x, x^3 - 2)^n ), 1)} /* Michael Somos, Aug 05 2009 */
    
  • PARI
    {a(n) = sum(k=0, n\3, 2^k * binomial(n, 3*k + 1))} /* Michael Somos, Aug 05 2009 */
    
  • PARI
    {a(n) = if( n<0, 0, polcoeff( (x - 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+1) 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+1). - Ralf Stephan, Aug 30 2004
From R. J. Mathar, Apr 01 2008: (Start)
O.g.f.: x*(1 - x)/(1 - 3*x + 3*x^2 - 3*x^3).
a(n+1) - a(n) = A052101(n). (End)

A097122 Expansion of (1-x)^2/((1-x)^3 - 3*x^3).

Original entry on oeis.org

1, 1, 1, 4, 13, 31, 70, 169, 421, 1036, 2521, 6139, 14998, 36661, 89545, 218644, 533941, 1304071, 3184966, 7778449, 18996733, 46394716, 113307745, 276726019, 675833686, 1650553981, 4031064961, 9844867684, 24043624093, 58720529071
Offset: 0

Views

Author

Paul Barry, Jul 25 2004

Keywords

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.

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1-x)^2/((1-x)^3-3x^3),{x,0,40}],x]
  • PARI
    a(n) = sum(k=0, n\3, binomial(n, 3*k) * 3^k); \\ Michel Marcus, Oct 11 2021

Formula

G.f.: (1-2*x+x^2)/(1-3*x+3*x^2-4*x^3).
a(n) = 3*a(n-1) - 3*a(n-2) + 4*a(n-3).
a(n) = Sum_{k=0..floor(n/3)} binomial(n, 3k) * 3^k.

A100138 a(n) = Sum_{k=0..floor(n/6)} C(n-3k,3k) * 2^(n-5k).

Original entry on oeis.org

1, 2, 4, 8, 16, 32, 66, 144, 336, 832, 2144, 5632, 14852, 38968, 101312, 260736, 664704, 1681152, 4226056, 10578080, 26407648, 65838848, 164095360, 409129472, 1020795408, 2549137824, 6371133120, 15935185792, 39878810624, 99837958144
Offset: 0

Views

Author

Paul Barry, Nov 06 2004

Keywords

Comments

Binomial transform of 1,1,1,1,1,1,3,3,9,9,21,... with g.f. (1-x)^2(1+x)^2/(1-3x^2+3x^4-3x^6)=(1+x)(1-x^2)^2/((1-x^2)^3-2x^6).

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[n-3k,3k]2^(n-5k),{k,0,Floor[n/6]}],{n,0,30}] (* or *) LinearRecurrence[{6,-12,8,0,0,2},{1,2,4,8,16,32},30] (* Harvey P. Dale, Dec 30 2019 *)

Formula

G.f.: (1-2x)^2/((1-2x)^3 - 2x^6).
a(n) = 6*a(n-1) - 12*a(n-2) + 8*a(n-3) + 2*a(n-6).

A093406 a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) + a(n-4).

Original entry on oeis.org

1, 3, 11, 31, 71, 145, 289, 601, 1321, 2979, 6683, 14743, 32111, 69697, 151777, 332113, 728689, 1598883, 3503627, 7668079, 16774775, 36704017, 80343361, 175916521, 385196761, 843365379, 1846290395, 4041672871, 8847607391, 19368919297, 42403014721, 92830645537
Offset: 1

Views

Author

Gary W. Adamson, Mar 28 2004

Keywords

Comments

a(n)/a(n-1) tends to 2.189207115... = 1 + 2^(1/4) = 1 + A010767.

Examples

			a(4) = 31, since M^4 * [1,1,1,1] = [3, 11, 31, 71].
		

References

  • E. J. Barbeau, Polynomials, Springer-Verlag NY Inc, 1989, p. 136.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{4,-6,4,1},{1,3,11,31},40] (* Harvey P. Dale, Jul 22 2013 *)

Formula

We use a 4 X 4 matrix corresponding to the characteristic polynomial (x - 1)^4 - 2 = 0 = x^4 - 4x^3 + 6x^2 - 4x - 1 = 0, being [0 1 0 0 / 0 0 1 0 / 0 0 0 1 / 1 4 -6 4]. Let the matrix = M. Perform M^n * [1, 1, 1, 1]. a(n) = the third term from the left, (the other 3 terms being offset members of the series).
a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)+a(n-4). G.f.: -x*(x^3+5*x^2-x+1)/ (x^4+4*x^3-6*x^2+4*x-1). [Colin Barker, Oct 21 2012]

Extensions

Corrected by T. D. Noe, Nov 08 2006
New name using recurrence from Colin Barker, Joerg Arndt, Apr 15 2021

A247584 a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + 3*a(n-5) with a(0) = a(1) = a(2) = a(3) = a(4) = 1.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 13, 43, 113, 253, 509, 969, 1849, 3719, 8009, 18027, 40897, 91257, 198697, 423777, 894081, 1886011, 4007301, 8594411, 18560081, 40181493, 86872293, 187197193, 402060793, 861827743, 1846685729, 3960390059, 8504658049, 18283290609, 39325827729
Offset: 0

Views

Author

Alexander Samokrutov, Sep 20 2014

Keywords

Comments

a(n)/a(n-1) tends to 2.1486... = 1 + 2^(1/5), the real root of the polynomial x^5 - 5*x^4 + 10*x^3 - 10*x^2 + 5*x - 3.
If x^5 = 2 and n >= 0, then there are unique integers a, b, c, d, g such that (1 + x)^n = a + b*x + c*x^2 + d*x^3 + g*x^4. The coefficient a is a(n) (from A052102). - Alexander Samokrutov, Jul 11 2015
If x=a(n), y=a(n+1), z=a(n+2), s=a(n+3), t=a(n+4) then x, y, z, s, t satisfies Diophantine equation (see link). - Alexander Samokrutov, Jul 11 2015

Crossrefs

Cf. A005531.

Programs

  • Magma
    [n le 5 select 1 else 5*Self(n-1) -10*Self(n-2) +10*Self(n-3) -5*Self(n-4) +3*Self(n-5): n in [1..40]]; // Vincenzo Librandi, Jul 11 2015
    
  • Maple
    m:=50; S:=series( (1-x)^4/(1 -5*x +10*x^2 -10*x^3 +5*x^4 -3*x^5), x, m+1):
    seq(coeff(S, x, j), j=0..m); # G. C. Greubel, Apr 15 2021
  • Mathematica
    LinearRecurrence[{5,-10,10,-5,3}, {1,1,1,1,1}, 50] (* Vincenzo Librandi, Jul 11 2015 *)
  • Maxima
    makelist(sum(2^k*binomial(n,5*k), k, 0, floor(n/5)), n, 0, 50); /* Alexander Samokrutov, Jul 11 2015 */
    
  • PARI
    Vec((1-x)^4/(1-5*x+10*x^2-10*x^3+5*x^4-3*x^5) + O(x^100)) \\ Colin Barker, Sep 22 2014
    
  • Sage
    [sum(2^j*binomial(n, 5*j) for j in (0..n//5)) for n in (0..50)] # G. C. Greubel, Apr 15 2021

Formula

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + 3*a(n-5).
a(n) = Sum_{k=0...floor(n/5)} (2^k*binomial(n,5*k)). - Alexander Samokrutov, Jul 11 2015
G.f.: (1-x)^4/(1 -5*x +10*x^2 -10*x^3 +5*x^4 -3*x^5). - Colin Barker, Sep 22 2014
Showing 1-7 of 7 results.