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 1-10 of 33 results. Next

A172497 Triangle T(n, k) = round( c(n)/(c(k)*c(n-k)) ) where c(n) = Product_{j=1..n} A029826(j+10), read by rows.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 4, 2, 2, 1, 1, 3, 6, 6, 6, 6, 3, 1, 1, 2, 6, 12, 6, 12, 6, 2, 1, 1, 4, 8, 24, 24, 24, 24, 8, 4, 1, 1, 3, 12, 24, 36, 72, 36, 24, 12, 3, 1, 1, 5, 15, 60, 60, 180, 180, 60, 60, 15, 5, 1, 1, 5, 25, 75, 150, 300, 450, 300, 150, 75, 25, 5, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 05 2010

Keywords

Examples

			The triangle begins as:
  1;
  1, 1;
  1, 1,  1;
  1, 1,  1,  1;
  1, 2,  2,  2,  1;
  1, 1,  2,  2,  1,  1;
  1, 2,  2,  4,  2,  2,  1;
  1, 3,  6,  6,  6,  6,  3,  1;
  1, 2,  6, 12,  6, 12,  6,  2,  1;
  1, 4,  8, 24, 24, 24, 24,  8,  4, 1;
  1, 3, 12, 24, 36, 72, 36, 24, 12, 3, 1;
		

Crossrefs

Cf. A029826.

Programs

  • Magma
    R:= PowerSeriesRing(Integers(), 100);
    b:= Coefficients(R!( 1/(1+x-x^3-x^4-x^5-x^6-x^7+x^9+x^10) ));
    c:= func< n | (&*[b[j]: j in [10..n+10]]) >;
    T:= func< n,k | Round(c(n)/(c(k)*c(n-k))) >;
    [T(n,k): k in [0..n], n in [1..12]]; // G. C. Greubel, Apr 20 2021
    
  • Mathematica
    b:= Drop[CoefficientList[Series[1/(1+x-x^3-x^4-x^5-x^6-x^7+x^9+x^10), {x,0,100}], x], 10];
    c[n_]:= Product[b[[j]], {j,n}];
    T[n_, k_]:= Round[c[n]/(c[k]*c[n-k])];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Apr 20 2021 *)
  • Sage
    @CachedFunction
    def A029826_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/(1+x-x^3-x^4-x^5-x^6-x^7+x^9+x^10) ).list()
    b=A029826_list(130)
    def c(n): return product(b[j] for j in (9..n+9))
    def T(n,k): return round(c(n)/(c(k)*c(n-k)))
    flatten([[T(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Apr 20 2021

Formula

T(n, k) = round( c(n)/(c(k)*c(n-k)) ) where c(n) = Product_{j=1..n} A029826(j+10).

Extensions

Definition corrected and edited by G. C. Greubel, Apr 20 2021

A173894 a(n) = ceiling(A029826(n)/2).

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 3, 3, 3, 4, 4, 5, 6, 7, 8, 10, 11, 14, 16, 19, 22, 25, 31, 35, 42, 49, 58, 68, 80, 94, 110, 130, 152, 180, 210, 248, 292, 343, 404, 474, 558, 656, 772, 908, 1068, 1256, 1478, 1738, 2045, 2406, 2829, 3328, 3914, 4605, 5416, 6371, 7494, 8815, 10369, 12197, 14347
Offset: 0

Views

Author

Roger L. Bagula, Nov 26 2010

Keywords

Crossrefs

Cf. A029826.

Programs

  • Magma
    R:= PowerSeriesRing(Integers(), 105);
    A029826:= Coefficients(R!( 1/(1+x-x^3-x^4-x^5-x^6-x^7+x^9+x^10) ));
    A173894:= func< n | Ceiling( A029826[n+1]/2 ) >;
    [A173894(n): n in [0..100]]; // G. C. Greubel, Apr 23 2021
    
  • Mathematica
    A029826 = CoefficientList[Series[1/(1+x-x^3-x^4-x^5-x^6-x^7+x^9+x^10), {x, 0, 250}], x];
    Table[Ceiling[A029826[[n+1]]/2], {n, 0, 100}] (* modified by G. C. Greubel, Apr 23 2021 *)
  • Sage
    A029826=[( 1/(1+x-x^3-x^4-x^5-x^6-x^7+x^9+x^10) ).series(x,n+1).list()[n] for n in (0..100)]
    def A173894(n): return ceil( A029826[n]/2 )
    [A173894(n) for n in (0..100)] # G. C. Greubel, Apr 23 2021

Formula

a(n) = ceiling(A029826(n)/2) = A029826(n) - floor(A029826(n)/2).

A172972 Subtraction triangle based on A029826: c(n)=Product[A029826(i),{i,0,n)];t(n,m)=c(n)-c(m)-c(n-m).

Original entry on oeis.org

-1, -1, -1, -1, -3, -1, -1, -1, -1, -1, -1, 0, 2, 0, -1, -1, -1, 2, 2, -1, -1, -1, -1, 1, 2, 1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, 1, 1, 0, 1, 1, -1, -1, -1, -1, 1, 1, 0, 0, 1, 1, -1, -1, -1, -1, 1, 1, 0, 0, 0, 1, 1, -1, -1
Offset: 0

Views

Author

Roger L. Bagula, Feb 06 2010

Keywords

Comments

Row sums are:
{-1, -2, -5, -4, 0, 0, 0, 0, 0, 0, 0,...}.

Examples

			{-1},
{-1, -1},
{-1, -3, -1},
{-1, -1, -1, -1},
{-1, 0, 2, 0, -1},
{-1, -1, 2, 2, -1, -1},
{-1, -1, 1, 2, 1, -1, -1},
{-1, -1, 1, 1, 1, 1, -1, -1},
{-1, -1, 1, 1, 0, 1, 1, -1, -1},
{-1, -1, 1, 1, 0, 0, 1, 1, -1, -1},
{-1, -1, 1, 1, 0, 0, 0, 1, 1, -1, -1}
		

Crossrefs

Programs

  • Mathematica
    (*A029826 Inverse of Salem polynomial : 1/(x^10 + x^9 - x^7 - x^6 - x^5 - x^4 - x^3 + x + 1).*)
    p[x_] = (x^(10) + x^9 - x^7 - x^6 - x^5 - x^4 - x^3 + x + 1); q[ x_] = Expand[x^10*p[1/x]]; a = Table[SeriesCoefficient[Series[1/ q[x], {x, 0, 100}], n], {n, 0, 100}];
    c[n_] := Product[a[[m]], {m, 1, n}];
    t[n_, m_] := c[n] - (c[m] + c[n - m]);
    Table[Table[t[n, m], {m, 0, n}], {n, 0, 10}];
    Flatten[%]

Formula

c(n)=Product[A029826(i),{i,0,n)];
t(n,m)=c(n)-c(m)-c(n-m)

A172986 a(0) = 0, a(n) = A029826(n+1) for n <= 20, otherwise a(n) = a(n - 1 - n % 20) + A029826(2 + n % 20 ).

Original entry on oeis.org

0, 1, -1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 2, 1, 2, 3, 2, 4, 3, 3, 5, 4, 4, 5, 4, 5, 4, 5, 5, 5, 5, 6, 5, 6, 7, 6, 8, 7, 8, 6, 8, 7, 7, 8, 7, 8, 7, 8, 8, 8, 8, 9, 8, 9, 10, 9, 11, 10, 11, 9, 11, 10, 10, 11, 10, 11, 10, 11, 11, 11, 11, 12, 11, 12, 13, 12, 14, 13, 14, 12, 14, 13, 13, 14, 13, 14, 13
Offset: 0

Views

Author

Roger L. Bagula, Feb 06 2010

Keywords

Crossrefs

Cf. A029826.

Programs

  • Mathematica
    p[x_] = (x^(10) + x^9 - x^7 - x^6 - x^5 - x^4 - x^3 + x + 1);
    q[x_] = Expand[x^10*p[1/x]];
    a = Table[SeriesCoefficient[Series[1/q[x], {x, 0, 50}], n], {n, 0, 20}];
    b[0] := 0;
    b[n_] := b[n] = If[n <= 20, a[[n]], b[n - 1 - Mod[n, 20]] + a[[1 + Mod[n, 20]]]];
    Table[b[n], {n, 0, 100}]

A117791 Expansion of 1/(1 - x - x^2 + x^4 - x^6).

Original entry on oeis.org

1, 1, 2, 3, 4, 6, 9, 13, 20, 30, 45, 68, 102, 153, 230, 345, 518, 778, 1168, 1754, 2634, 3955, 5939, 8918, 13391, 20108, 30194, 45339, 68081, 102230, 153508, 230507, 346128, 519744, 780445, 1171912, 1759737, 2642412, 3967832, 5958076, 8946616, 13434192
Offset: 0

Views

Author

Roger L. Bagula, Apr 15 2006

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50); Coefficients(R!(1/(1-x-x^2+x^4-x^6))); // G. C. Greubel, Nov 03 2018
    
  • Maple
    seq(coeff(series(1/(1 -x -x^2 +x^4 -x^6), x, n+1), x, n), n = 0..50); # G. C. Greubel, Dec 05 2019
  • Mathematica
    CoefficientList[Series[1/(1 -x -x^2 +x^4 -x^6), {x, 0, 50}], x]
  • PARI
    Vec(1/(1 -x -x^2 +x^4 -x^6)+O(x^50)) \\ Charles R Greathouse IV, Sep 23 2012
    
  • Sage
    def A117791_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/(1 -x -x^2 +x^4 -x^6) ).list()
    A117791_list(50) # G. C. Greubel, Dec 05 2019

Formula

a(n) = a(n-1) + a(n-2) - a(n-4) + a(n-6). - Ilya Gutkovskiy, Nov 16 2016

Extensions

Edited by N. J. A. Sloane, Nov 08 2006

A204631 Expansion of 1/(1 - x - x^2 + x^5 - x^7).

Original entry on oeis.org

1, 1, 2, 3, 5, 7, 11, 17, 26, 40, 62, 96, 148, 229, 354, 547, 845, 1306, 2018, 3118, 4818, 7445, 11504, 17776, 27468, 42444, 65585, 101343, 156597, 241976, 373905, 577764, 892770, 1379522, 2131659, 3293873, 5089744, 7864752, 12152738, 18778601, 29016988
Offset: 0

Views

Author

Roger L. Bagula, Jan 17 2012

Keywords

Comments

Limiting ratio is 1.5452156..., the real root of x^7 - x^6 - x^5 + x^2 - 1.

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x-x^2+x^5-x^7))); // G. C. Greubel, Nov 03 2018
  • Maple
    seq(coeff(series(1/(1-x-x^2+x^5-x^7), x, n+1), x, n), n = 0..50); # G. C. Greubel, Mar 16 2020
  • Mathematica
    CoefficientList[Series[1/(1 - x - x^2 + x^5 - x^7), {x, 0, 50}], x]
    LinearRecurrence[{1,1,0,0,-1,0,1},{1,1,2,3,5,7,11},50] (* Harvey P. Dale, Aug 28 2013 *)
  • PARI
    my(x='x+O('x^50)); Vec(1/(1-x-x^2+x^5-x^7)) \\ G. C. Greubel, Nov 16 2016
    

Formula

a(n) = a(n-1) + a(n-2) - a(n-5) + a(n-7). - Franck Maminirina Ramaharo, Nov 02 2018

A225391 Expansion of 1/(1 - x - x^2 - x^6 + x^8).

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 14, 23, 38, 63, 104, 172, 285, 472, 781, 1293, 2140, 3542, 5863, 9705, 16064, 26590, 44013, 72852, 120588, 199603, 330392, 546880, 905221, 1498363, 2480159, 4105273, 6795236, 11247786, 18617851, 30817120, 51009909, 84433939, 139758925
Offset: 0

Views

Author

Roger L. Bagula, May 06 2013

Keywords

Comments

Limiting ratio is 1.65525..., the largest real root of 1 - x^2 - x^6 - x^7 + x^8.

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x-x^2-x^6+x^8))); // G. C. Greubel, Nov 03 2018
  • Mathematica
    CoefficientList[Series[1/(1 - x - x^2 - x^6 + x^8), {x, 0, 50}], x]
    LinearRecurrence[{1,1,0,0,0,1,0,-1}, {1,1,2,3,5,8,14,23}, 100] (* G. C. Greubel, Nov 16 2016 *)
  • PARI
    Vec(1/(1-x-x^2-x^6+x^8) + O(x^50)) \\ G. C. Greubel, Nov 16 2016
    

Formula

a(n) = a(n-1) + a(n-2) + a(n-6) - a(n-8). - Franck Maminirina Ramaharo, Nov 02 2018

A225482 Expansion of 1/(1 - x^3 - x^4 - x^5 + x^8).

Original entry on oeis.org

1, 0, 0, 1, 1, 1, 1, 2, 2, 3, 4, 4, 6, 8, 10, 12, 16, 21, 26, 34, 43, 55, 71, 91, 116, 148, 191, 244, 312, 400, 512, 656, 840, 1076, 1377, 1764, 2260, 2893, 3705, 4745, 6077, 7782, 9966, 12763, 16344, 20932, 26806, 34328, 43962, 56300, 72100, 92333, 118246
Offset: 0

Views

Author

Roger L. Bagula, May 08 2013

Keywords

Comments

Limiting ratio is 1.28064..., the largest real root of 1 - x^3 - x^4 - x^5 + x^8: 1.280638156267757596701902532710 is a candidate for the smallest degree-8 Salem number.

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^3-x^4-x^5+x^8))); // G. C. Greubel, Nov 03 2018
  • Mathematica
    CoefficientList[Series[1/(1 - x^3 - x^4 - x^5 + x^8), {x, 0, 50}], x]
    LinearRecurrence[{0,0,1,1,1,0,0,-1}, {1,0,0,1,1,1,1,2}, 100] (* G. C. Greubel, Nov 16 2016 *)
  • PARI
    Vec(1/(1-x^3-x^4-x^5+x^8)+O(x^99)) \\ Charles R Greathouse IV, May 08 2013
    

Formula

a(n) = a(n-3) + a(n-4) + a(n-5) - a(n-8). - Franck Maminirina Ramaharo, Nov 02 2018

Extensions

More terms from Franck Maminirina Ramaharo, Nov 02 2018

A143419 G.f.: 1/p(x), where p(x) = degree 22 Salem polynomial p(x) = x^22 + x^21 - x^19 - 2*x^18 - 3*x^17 - 3*x^16 - 2*x^15 + 2*x^13 + 4*x^12 + 5*x^11 + 4*x^10 + 2*x^9 - 2*x^7 - 3*x^6 - 3*x^5 - 2*x^4 - x^3 + x + 1.

Original entry on oeis.org

1, -1, 1, 0, 1, 1, 1, 2, 2, 4, 4, 7, 9, 12, 17, 23, 32, 44, 60, 83, 113, 156, 214, 294, 403, 554, 760, 1044, 1433, 1967, 2701, 3708, 5091, 6988, 9596, 13172, 18085, 24828, 34086, 46797, 64246, 88203, 121092, 166246, 228237, 313343, 430185, 590594, 810819
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Oct 23 2008

Keywords

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(x^22 +x^21-x^19-2*x^18-3*x^17-3*x^16-2*x^15+2*x^13+4*x^12+5*x^11 + 4*x^10+2*x^9-2*x^7-3*x^6-3*x^5-2*x^4-x^3+x+1))); // G. C. Greubel, Nov 03 2018
  • Mathematica
    f[x_] = x^22 + x^21 - x^19 - 2*x^18 - 3*x^17 - 3*x^16 - 2*x^15 + 2*x^13 + 4*x^12 + 5*x^11 + 4*x^10 + 2*x^9 - 2*x^7 - 3*x^6 - 3*x^5 - 2*x^4 - x^3 + x + 1;
    CoefficientList[Series[1/f[x], {x, 0, 50}], x]
    LinearRecurrence[{-1,0,1,2,3,3,2,0,-2,-4,-5,-4,-2,0,2,3,3,2,1,0,-1,-1},{1,-1,1,0,1,1,1,2,2,4,4,7,9,12,17,23,32,44,60,83,113,156},50] (* Harvey P. Dale, Aug 18 2024 *)
  • PARI
    p(x)=x^22 + x^21 - x^19 - 2*x^18 - 3*x^17 - 3*x^16 - 2*x^15 + 2*x^13 + 4*x^12 + 5*x^11 + 4*x^10 + 2*x^9 - 2*x^7 - 3*x^6 - 3*x^5 - 2*x^4 - x^3 + x + 1; Vec(1/p(x)+O(x^60)) \\ Charles R Greathouse IV, Feb 13 2011
    

Formula

a(n) = -a(n-1) + a(n-3) + 2*a(n-4) + 3*a(n-5) + 3*a(n-6) + 2*a(n-7) - 2*a(n-9) - 4*a(n-10) - 5*a(n-11) - 4*a(n-12) - 2*a(n-13) + 2*a(n-15) + 3*a(n-16) + 3*a(n-17) + 2*a(n-18) + a(n-19) - a(n-21) - a(n-22). - Franck Maminirina Ramaharo, Oct 30 2018

Extensions

Edited by N. J. A. Sloane, Dec 12 2008
More terms from Sean A. Irvine, Feb 13 2011
Offset corrected, and more terms from Franck Maminirina Ramaharo, Nov 02 2018

A173911 Expansion of 1/(1 - x + x^2 - x^3 - x^6 + x^7 - x^8 + x^9 - x^10 + x^11 - x^12 -x^15 + x^16 - x^17 + x^18).

Original entry on oeis.org

1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 4, 4, 5, 6, 7, 8, 10, 12, 14, 16, 19, 23, 28, 33, 39, 46, 55, 66, 78, 92, 110, 131, 155, 184, 219, 260, 309, 368, 437, 519, 617, 733, 871, 1036, 1231, 1462, 1737, 2065, 2454, 2916, 3465, 4118, 4894, 5816, 6911, 8213
Offset: 0

Views

Author

Roger L. Bagula, Nov 26 2010

Keywords

Comments

Limiting ratio is 1.188368147508223588... = A219300.

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50); Coefficients(R!(1/(1-x+x^2-x^3-x^6+x^7-x^8+x^9-x^10+x^11-x^12-x^15+x^16-x^17+x^18))); // G. C. Greubel, Nov 03 2018
    
  • Maple
    seq(coeff(series(1/(1-x+x^2-x^3-x^6+x^7-x^8+x^9-x^10+x^11-x^12-x^15+x^16 -x^17+x^18), x, n+1), x, n), n = 0..50); # G. C. Greubel, Dec 15 2019
  • Mathematica
    CoefficientList[Series[1/(1-x+x^2-x^3-x^6+x^7-x^8+x^9-x^10+x^11-x^12-x^15+x^16 -x^17+x^18), {x,0,50}], x]
    LinearRecurrence[{1,-1,1,0,0,1,-1,1,-1,1,-1,1,0,0,1,-1,1,-1},{1,1,0,0,1,1,1,1,1,1,2,2,2,3,4,4,5,6},60] (* Harvey P. Dale, Apr 02 2024 *)
  • PARI
    my(x='x+O('x^50)); Vec(1/(1-x+x^2-x^3-x^6+x^7-x^8+x^9-x^10+x^11-x^12-x^15+ x^16-x^17+x^18)) \\ G. C. Greubel, Nov 03 2018
    
  • Sage
    def A173911_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/(1-x+x^2-x^3-x^6+x^7-x^8+x^9-x^10+x^11-x^12-x^15+x^16 -x^17+x^18) ).list()
    A173911_list(50) # G. C. Greubel, Dec 15 2019

Formula

a(n) = a(n-1) - a(n-2) + a(n-3) + a(n-6) - a(n-7) + a(n-8) - a(n-9) + a(n-10) - a(n-11) + a(n-12) + a(n-15) - a(n-16) + a(n-17) - a(n-16). - Franck Maminirina Ramaharo, Nov 02 2018
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