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 26 results. Next

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

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

A225393 Expansion of 1/(1 - x - x^2 + x^6 - x^8).

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 12, 19, 30, 47, 74, 116, 183, 288, 453, 713, 1122, 1766, 2779, 4373, 6882, 10830, 17043, 26820, 42206, 66419, 104522, 164484, 258845, 407339, 641021, 1008761, 1587466, 2498162, 3931305, 6186612, 9735741, 15320931, 24110227, 37941757, 59708145
Offset: 0

Views

Author

Roger L. Bagula, May 06 2013

Keywords

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},{1,1,2,3,5,8,12,19},50] (* 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

G.f.: 1/(1 - x - x^2 + x^6 - x^8).
a(n) = a(n-1) + a(n-2) - a(n-6) + a(n-8). - Ilya Gutkovskiy, Nov 16 2016

A225394 Expansion of 1/(1 - x - x^2 + x^7 - x^9).

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 13, 20, 32, 51, 81, 129, 205, 326, 519, 826, 1314, 2091, 3327, 5294, 8424, 13404, 21328, 33937, 54000, 85924, 136721, 217548, 346159, 550803, 876429, 1394560, 2219002, 3530841, 5618219, 8939622, 14224586, 22633938, 36014767, 57306132, 91184618
Offset: 0

Views

Author

Roger L. Bagula, May 06 2013

Keywords

Comments

Limiting ratio is 1.59118..., the largest real root of -1 + x^2 - x^7 - x^8 + x^9 = 0.

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x-x^2+x^7-x^9))); // G. C. Greubel, Nov 03 2018
  • Mathematica
    CoefficientList[Series[1/(1 - x - x^2 + x^7 - x^9), {x, 0, 50}], x]
    LinearRecurrence[{1,1,0,0,0,0,-1,0,1}, {1,1,2,3,5,8,13,20,32}, 50] (* G. C. Greubel, Nov 16 2016 *)
  • PARI
    Vec(1/(1-x-x^2+x^7-x^9) + O(x^50)) \\ G. C. Greubel, Nov 16 2016
    

Formula

a(n) = a(n-1) + a(n-2) - a(n-7) + a(n-9). - Ilya Gutkovskiy, Nov 16 2016

A225499 Expansion of 1/(1 - x + x^2 - x^3 - x^6 - x^9 + x^10 - x^11 + x^12).

Original entry on oeis.org

1, 1, 0, 0, 1, 1, 1, 2, 2, 2, 3, 4, 4, 5, 7, 9, 11, 13, 16, 20, 25, 31, 39, 48, 59, 74, 92, 113, 140, 175, 217, 269, 334, 414, 513, 637, 791, 981, 1217, 1510, 1874, 2325, 2884, 3578, 4440, 5509, 6835, 8481, 10522, 13054, 16197, 20097, 24934, 30936, 38384
Offset: 0

Views

Author

Roger L. Bagula, May 09 2013

Keywords

Comments

Limiting ratio is 1.24073..., the largest real root of 1 - x + x^2 - x^3 - x^6 - x^9 + x^10 - x^11 + x^12: 1.240726423652541392056148161575
is a candidate for the smallest degree-12 Salem number.

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1 -x +x^2 -x^3 -x^6 -x^9 +x^10 -x^11 +x^12))); // G. C. Greubel, Nov 03 2018
  • Mathematica
    CoefficientList[Series[1/(1 - x + x^2 - x^3 - x^6 - x^9 + x^10 - x^11 + x^12), {x, 0, 50}], x]
    LinearRecurrence[{1,-1,1,0,0,1,0,0,1,-1,1,-1},{1,1,0,0,1,1,1,2,2,2,3,4},100] (* G. C. Greubel, Nov 16 2016 *)
  • PARI
    Vec(1/(1 -x +x^2 -x^3 -x^6 -x^9 +x^10 -x^11 +x^12) + O(x^50)) \\ G. C. Greubel, Nov 16 2016
    

Formula

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

A143438 a(n) = a(n-2) + a(n-3) + a(n-4) - a(n-6), with a(0) = a(2) = a(3) = 1, a(1) = 0 and a(4) = a(5) = 2.

Original entry on oeis.org

1, 0, 1, 1, 2, 2, 3, 5, 6, 9, 12, 18, 24, 34, 48, 67, 94, 131, 185, 258, 362, 507, 711, 996, 1395, 1956, 2740, 3840, 5380, 7540, 10565, 14804, 20745, 29069, 40734, 57078, 79983, 112077, 157050, 220069, 308376, 432118, 605512, 848486, 1188956, 1666047, 2334578
Offset: 0

Views

Author

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

Keywords

Comments

Expansion of 1/p(x), where p(x) = 1 - x^2 - x^3 - x^4 + x^6 is a Salem polynomial.

Crossrefs

Programs

  • GAP
    a:=[1,0,1,1,2,2];; for n in [7..50] do a[n]:=a[n-2]+a[n-3]+a[n-4]-a[n-6]; od; a; # G. C. Greubel, Dec 06 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 50); Coefficients(R!(1/(1 -x^2-x^3-x^4+x^6))); // G. C. Greubel, Nov 03 2018
    
  • Maple
    seq(coeff(series(1/(1-x^2-x^3-x^4+x^6), x, n+1), x, n), n = 0..50); # G. C. Greubel, Dec 06 2019
  • Mathematica
    CoefficientList[Series[1/(1-x^2-x^3-x^4+x^6), {x, 0, 50}], x]
    LinearRecurrence[{0,1,1,1,0,-1}, {1,0,1,1,2,2}, 50] (* G. C. Greubel, Dec 06 2019 *)
  • Maxima
    makelist(ratcoef(taylor(1/(1 -x^2 -x^3 -x^4 +x^6), x, 0, n), x, n), n, 0, 50); /* Franck Maminirina Ramaharo, Oct 31 2018 */
    
  • PARI
    my(x='x+O('x^50)); Vec(1/(1-x^2-x^3-x^4+x^6)) \\ G. C. Greubel, Nov 03 2018
    
  • Sage
    def A143438_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P(1/(1-x^2-x^3-x^4+x^6)).list()
    A143438_list(50) # G. C. Greubel, Dec 06 2019
    

Formula

G.f.: 1/(1 - x^2 - x^3 - x^4 + x^6). - Colin Barker, Nov 24 2012

Extensions

Edited, new name (after Colin Barker), more terms, and offset corrected by Franck Maminirina Ramaharo, Oct 30 2018

A143472 Expansion of 1/(1 - x^3 - x^5 - x^7 + x^10), inverse of a Salem polynomial.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 1, 1, 2, 1, 2, 3, 3, 4, 5, 6, 7, 9, 11, 14, 17, 20, 26, 31, 38, 48, 58, 72, 88, 108, 134, 164, 202, 249, 306, 376, 463, 570, 701, 863, 1061, 1306, 1607, 1976, 2433, 2993, 3682, 4531, 5574, 6859, 8439, 10383, 12776, 15719, 19340, 23796
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Oct 24 2008

Keywords

Comments

The ratio productive positive root is 1.2303914344072246.

Crossrefs

Programs

  • Magma
    m:=50; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^3-x^5-x^7+x^10))); // G. C. Greubel, Nov 03 2018
  • Mathematica
    CoefficientList[Series[1/(1 - x^3 - x^5 - x^7 + x^10), {x, 0, 50}], x]
  • Maxima
    makelist(ratcoef(taylor(1/(1 - x^3 - x^5 - x^7 + x^10), x, 0, n), x, n), n, 0, 50); /* Franck Maminirina Ramaharo, Nov 02 2018 */
    
  • PARI
    x='x+O('x^50); Vec(1/(1-x^3-x^5-x^7+x^10)) \\ G. C. Greubel, Nov 03 2018
    

Formula

G.f.: 1/(1 - x^3 - x^5 - x^7 + x^10). - Colin Barker, Oct 23 2013
a(n) = a(n-3) + a(n-5) + a(n-7) - a(n-10). - Franck Maminirina Ramaharo, Oct 30 2018

Extensions

More terms from Colin Barker, Oct 23 2013
New name after Colin Barker's formula by Franck Maminirina Ramaharo, Nov 03 2018
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