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 11 results. Next

A047859 a(n) = T(2, n), where T is the array given by A047858.

Original entry on oeis.org

1, 4, 11, 27, 63, 143, 319, 703, 1535, 3327, 7167, 15359, 32767, 69631, 147455, 311295, 655359, 1376255, 2883583, 6029311, 12582911, 26214399, 54525951, 113246207, 234881023, 486539263, 1006632959, 2080374783, 4294967295, 8858370047, 18253611007, 37580963839
Offset: 0

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n-th difference of a(n), a(n-1), ..., a(0) is (3, 4, 5, ...).
From Gus Wiseman, Oct 14 2022: (Start)
Also the number of compositions of 2*(n+1) whose maximum part is n+1. These are compositions of 2*(n+1) whose maximum part equals the sum of their remaining parts. For example, the a(0) = 1 through a(2) = 11 compositions are:
(1,1) (2,2) (3,3)
(1,1,2) (1,2,3)
(1,2,1) (1,3,2)
(2,1,1) (2,1,3)
(2,3,1)
(3,1,2)
(3,2,1)
(1,1,1,3)
(1,1,3,1)
(1,3,1,1)
(3,1,1,1)
For length instead of maximum we have A001700.
These compositions are ranked by A357708. (End)

Crossrefs

Programs

  • Magma
    [(n+4)*2^(n-1)-1: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • PARI
    Vec((1-x-x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Aug 24 2016

Formula

Main diagonal of the array defined by: T(0, j) = j + 1 for j >= 0, T(i, 0) = i + 1 for i >= 0, T(i, j)= T(i-1, j-1) + T(i-1, j) + 1. a(n) = (n + 4)*2^(n-1) - 1. - Benoit Cloitre, Jun 17 2003
a(0) = 1, a(1) = 4, a(2) = 11, a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3). - Vincenzo Librandi, Sep 28 2011
G.f.: (1 - x - x^2)/((1 - x)*(1 - 2*x)^2). - Colin Barker, Aug 24 2016
a(n) = A045623(n) - 1. - Gus Wiseman, Oct 14 2022
E.g.f.: exp(x)*(exp(x)*(2 + x) - 1). - Stefano Spezia, Jan 02 2023

A047860 a(n) = T(3,n), array T given by A047858.

Original entry on oeis.org

1, 5, 14, 34, 78, 174, 382, 830, 1790, 3838, 8190, 17406, 36862, 77822, 163838, 344062, 720894, 1507326, 3145726, 6553598, 13631486, 28311550, 58720254, 121634814, 251658238, 520093694, 1073741822, 2214592510, 4563402750
Offset: 0

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The Wikipedia article on L-system Example 2 is "Pythagoras Tree" given by the axiom: 0 and rules: 1 -> 11, 0 -> 1[0]0. The length of the n-th string of symbols is a(n). This interpretation leads to a matrix power formula for a(n). - Michael Somos, Jan 12 2015

Examples

			G.f. = 1 + 5*x + 14*x^2 + 34*x^3 + 78*x^4 + 174*x^5 + 382*x^6 + 830*x^7 + ...
Using the Pythagoras Tree L-system, a(0) = #0 = 1, a(1) = #1[0]0 = 5, a(2) = #11[1[0]0]1[0]0 = 14. - _Michael Somos_, Jan 12 2015
		

Crossrefs

n-th difference of a(n), a(n-1), ..., a(0) is (4, 5, 6, ...).
First differences of A027993.

Programs

  • Magma
    [2^(n-1)*(n+6)-2: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • Mathematica
    LinearRecurrence[{5,-8,4},{1,5,14},30] (* Harvey P. Dale, Sep 29 2012 *)
  • PARI
    {a(n) = if( n<0, 0, [1, 1, 1, 1] * [2, 0, 0, 0; 1, 2, 0, 0; 1, 0, 1, 0; 1, 0, 0, 1]^n * [1, 0, 0, 0]~ )}; /* Michael Somos, Jan 12 2015 */
    
  • PARI
    a(n)=([0,1,0; 0,0,1; 4,-8,5]^n*[1;5;14])[1,1] \\ Charles R Greathouse IV, Jul 19 2016

Formula

Main diagonal of the array defined by T(0, j)=j+1 j>=0, T(i, 0)=i+1 i>=0, T(i, j)=T(i-1, j-1)+T(i-1, j)+ 2; a(n)=2^(n-1)*(n+6)-2. - Benoit Cloitre, Jun 17 2003
a(0)=1, a(1)=5, a(2)=14, a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3). - Vincenzo Librandi, Sep 28 2011

A036542 a(n) = T(n, n), array T given by A047858.

Original entry on oeis.org

1, 3, 11, 34, 93, 236, 571, 1338, 3065, 6904, 15351, 33782, 73717, 159732, 344051, 737266, 1572849, 3342320, 7077871, 14942190, 31457261, 66060268, 138412011, 289406954, 603979753, 1258291176, 2617245671, 5435817958, 11274289125, 23353884644, 48318382051
Offset: 0

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Keywords

Programs

  • Mathematica
    LinearRecurrence[{6,-13,12,-4},{1,3,11,34},40] (* Harvey P. Dale, Jul 21 2024 *)
  • PARI
    Vec((1-3*x+6*x^2-5*x^3)/((1-x)^2*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 20 2016

Formula

a(n) = 3*n * 2^(n-1) - n + 1.
From Colin Barker, Feb 20 2016: (Start)
a(n) = 6*a(n-1)-13*a(n-2)+12*a(n-3)-4*a(n-4) for n>3.
G.f.: (1-3*x+6*x^2-5*x^3) / ((1-x)^2*(1-2*x)^2).
(End)

A047861 a(n) = T(4,n), array T given by A047858.

Original entry on oeis.org

1, 6, 17, 41, 93, 205, 445, 957, 2045, 4349, 9213, 19453, 40957, 86013, 180221, 376829, 786429, 1638397, 3407869, 7077885, 14680061, 30408701, 62914557, 130023421, 268435453, 553648125, 1140850685, 2348810237, 4831838205, 9932111869, 20401094653, 41875931133
Offset: 0

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n-th difference of a(n), a(n-1), ..., a(0) is (5, 6, 7, ...).

Programs

  • Magma
    [2^(n-1)*(n+8)-3: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • PARI
    Vec((1+x-5*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 17 2016

Formula

Main diagonal of the array defined by T(0, j)=j+1 j>=0, T(i, 0)=i+1 i>=0, T(i, j)=T(i-1, j-1)+T(i-1, j)+ 3; a(n)=2^(n-1)*(n+8)-3. - Benoit Cloitre, Jun 17 2003
a(0)=1, a(1)=6, a(2)=17, a(n) = 5*a(n-1) -8*a(n-2) +4*a(n-3). - Vincenzo Librandi, Sep 28 2011
G.f.: (1+x-5*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Feb 17 2016

A047862 a(n) = T(5,n), array T given by A047858.

Original entry on oeis.org

1, 7, 20, 48, 108, 236, 508, 1084, 2300, 4860, 10236, 21500, 45052, 94204, 196604, 409596, 851964, 1769468, 3670012, 7602172, 15728636, 32505852, 67108860, 138412028, 285212668, 587202556, 1207959548, 2483027964, 5100273660, 10468982780, 21474836476
Offset: 0

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n-th difference of a(n), a(n-1), ..., a(0) is (6, 7, 8, ...).
More generally the main diagonal of the array defined by T(0,j) = j+1 with j>=0, T(i,0) = i+1 with i>=0, T(i,j) = T(i-1,j-1) + T(i-1,j) + A, is given by T(n,n) = 2^(n-1)*(n+2*A+2)-A. - Benoit Cloitre, Jun 17 2003

Programs

  • Magma
    [2^(n-1)*(n+10)-4: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • PARI
    Vec((1+2*x-7*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 18 2016

Formula

From Benoit Cloitre, Jun 17 2003: (Start)
Main diagonal of the array defined by T(0, j) = j+1 with j>=0, T(i, 0) = i+1 with i>=0, T(i,j) = T(i-1,j-1)+T(i-1,j)+ 4. Therefore, for i = j = n:
a(n) = 2^(n-1)*(n+10)-4. (End)
a(0)=1, a(1)=7, a(2)=20; for n>2, a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3). - Vincenzo Librandi, Sep 28 2011
a(n) = 2^(n-1)*(n+10)-4. G.f.: (1+2*x-7*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Feb 18 2016

A048467 a(n) = T(6,n), array T given by A047858.

Original entry on oeis.org

1, 8, 23, 55, 123, 267, 571, 1211, 2555, 5371, 11259, 23547, 49147, 102395, 212987, 442363, 917499, 1900539, 3932155, 8126459, 16777211, 34603003, 71303163, 146800635, 301989883, 620756987, 1275068411, 2617245691
Offset: 0

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Crossrefs

n-th difference of a(n), a(n-1), ..., a(0) is (7, 8, 9, ...).

Programs

  • Magma
    [2^(n-1)*(n+12)-5: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • Mathematica
    LinearRecurrence[{5,-8,4},{1,8,23},30] (* or *) CoefficientList[ Series[ (-9x^2+3x+1)/((1-x)(1-2x)^2),{x,0,30}],x] (* Harvey P. Dale, Jul 07 2011 *)
  • PARI
    Vec((-9*x^2+3*x+1)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Andrew Howroyd, Feb 15 2018

Formula

G.f.: (-9*x^2 + 3*x + 1)/((1-x)*(1-2*x)^2).
a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3). - Harvey P. Dale, Jul 07 2011
a(n) = 2^(n-1)*(n+12) - 5. - Vincenzo Librandi, Sep 28 2011

A048468 a(n) = T(7,n), array T given by A047858.

Original entry on oeis.org

1, 9, 26, 62, 138, 298, 634, 1338, 2810, 5882, 12282, 25594, 53242, 110586, 229370, 475130, 983034, 2031610, 4194298, 8650746, 17825786, 36700154, 75497466, 155189242, 318767098, 654311418, 1342177274, 2751463418, 5637144570, 11542724602, 23622320122
Offset: 0

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n-th difference of a(n), a(n-1), ..., a(0) is (8, 9, 10, ...).

Programs

  • Magma
    [2^(n-1)*(n+14)-6: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • Mathematica
    LinearRecurrence[{5,-8,4},{1,9,26},30] (* Harvey P. Dale, Apr 19 2012 *)
  • PARI
    Vec((1+4*x-11*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 18 2016

Formula

a(n) = 2^(n-1)*(n+14)-6. a(0)=1, a(1)=9, a(2)=26, a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3). - Vincenzo Librandi, Sep 28 2011
a(n) = 2^(n-1)*(n+14)-6. G.f.: (1+4*x-11*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Feb 18 2016

A048469 a(n) = T(8,n), array T given by A047858.

Original entry on oeis.org

1, 10, 29, 69, 153, 329, 697, 1465, 3065, 6393, 13305, 27641, 57337, 118777, 245753, 507897, 1048569, 2162681, 4456441, 9175033, 18874361, 38797305, 79691769, 163577849, 335544313, 687865849, 1409286137, 2885681145, 5905580025, 12079595513, 24696061945
Offset: 0

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Comments

n-th difference of a(n), a(n-1), ..., a(0) is (9, 10, 11, ...).

Programs

  • Magma
    [2^(n-1)*(n+16)-7: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
  • Mathematica
    LinearRecurrence[{5,-8,4},{1,10,29},40] (* Harvey P. Dale, Aug 15 2020 *)

Formula

Main diagonal of the array defined by T(0, j) = j+1 for j>=0, T(i, 0) = i+1 for i>=0, T(i, j) = T(i-1, j-1) + T(i-1, j) + 7. - Benoit Cloitre, Jun 17 2003
a(n) = 2^(n-1)*(n+16)-7. a(0)=1, a(1)=10, a(2)=29, a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3). - Vincenzo Librandi, Sep 28 2011
G.f.: (1+5*x-13*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Feb 18 2016

A195857 a(n) = T(9, n), array T given by A047858.

Original entry on oeis.org

1, 11, 32, 76, 168, 360, 760, 1592, 3320, 6904, 14328, 29688, 61432, 126968, 262136, 540664, 1114104, 2293752, 4718584, 9699320, 19922936, 40894456, 83886072, 171966456, 352321528, 721420280, 1476395000, 3019898872, 6174015480, 12616466424, 25769803768
Offset: 0

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Author

Vincenzo Librandi, Sep 28 2011

Keywords

Programs

  • Magma
    [2^(n-1)*(n+18)-8: n in [0..30]]
    
  • PARI
    Vec((1+6*x-15*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Aug 24 2016

Formula

a(n) = 2^(n-1)*(n+18)-8.
a(0)=1, a(1)=11, a(2)=32, a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3).
G.f.: (1+6*x-15*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Aug 24 2016

A195858 a(n) = T(10, n), array T given by A047858.

Original entry on oeis.org

1, 12, 35, 83, 183, 391, 823, 1719, 3575, 7415, 15351, 31735, 65527, 135159, 278519, 573431, 1179639, 2424823, 4980727, 10223607, 20971511, 42991607, 88080375, 180355063, 369098743, 754974711, 1543503863, 3154116599, 6442450935, 13153337335, 26843545591
Offset: 0

Views

Author

Vincenzo Librandi, Sep 28 2011

Keywords

Crossrefs

Cf. A047858.

Programs

  • Magma
    [2^(n-1)*(n+20)-9: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
    
  • Mathematica
    LinearRecurrence[{5,-8,4},{1,12,35},40] (* Harvey P. Dale, Jul 24 2019 *)
  • PARI
    Vec((1+7*x-17*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Aug 24 2016

Formula

a(n) = 2^(n-1)*(n+20)-9.
a(0)=1, a(1)=12, a(2)=35, a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3).
G.f.: (1+7*x-17*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Aug 24 2016
Showing 1-10 of 11 results. Next