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.

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A128079 a(n) = Sum_{k=0..n} A000984(k)*A001263(n+1,k+1), where A000984 is the central binomial coefficients and A001263 is the Narayana triangle.

Original entry on oeis.org

1, 3, 13, 69, 411, 2633, 17739, 124029, 892327, 6567285, 49235715, 374841195, 2890994445, 22545855855, 177524073021, 1409591810133, 11275693221519, 90792020672429, 735367765159347, 5987665336600683, 48987680485918149
Offset: 0

Views

Author

Paul D. Hanna, Feb 23 2007

Keywords

Examples

			Illustrate a(n) = Sum_{k=0..n} A000984(k)*A001263(n+1,k+1) by:
a(2) = 1*(1) + 2*(3) + 6*(1) = 13;
a(3) = 1*(1) + 2*(6) + 6*(6) + 20*(1) = 69;
a(4) = 1*(1) + 2*(10)+ 6*(20)+ 20*(10)+ 70*(1) = 411.
The Narayana triangle A001263(n+1,k+1) = C(n,k)*C(n+1,k)/(k+1) begins:
1;
1, 1;
1, 3, 1;
1, 6, 6, 1;
1, 10, 20, 10, 1;
1, 15, 50, 50, 15, 1; ...
		

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[2*k,k]*Binomial[n,k]*Binomial[n+1,k]/(k+1),{k,0,n}],{n,0,20}] (* Vaclav Kotesovec, Oct 20 2012 *)
  • PARI
    {a(n)=sum(k=0,n,binomial(2*k,k)*binomial(n,k)*binomial(n+1,k)/(k+1))}

Formula

a(n) = Sum_{k=0..n} C(2k,k)*C(n,k)*C(n+1,k)/(k+1).
Recurrence: (n+1)*(n+2)*a(n) = (7*n^2+11*n+6)*a(n-1) + 3*(7*n^2-19*n+6)*a(n-2) - 27*(n-2)*(n-1)*a(n-3) . - Vaclav Kotesovec, Oct 20 2012
a(n) ~ 3^(2*n+7/2)/(8*Pi*n^2) . - Vaclav Kotesovec, Oct 20 2012
a(n) = ((n+3)^2*A005802(n+1)-(n-3)*(n+1)*A005802(n))/12. - Mark van Hoeij, Nov 12 2023

A132819 A001263 * A127773.

Original entry on oeis.org

1, 1, 3, 1, 9, 6, 1, 18, 36, 10, 1, 30, 120, 100, 15, 1, 45, 300, 500, 225, 21, 1, 63, 630, 1750, 1575, 441, 28, 1, 84, 1176, 4900, 7350, 4116, 784, 36, 1, 108, 2016, 11760, 26460, 24696, 9408, 1296, 45, 1, 135, 3240, 25200, 79380, 111132, 70560, 19440
Offset: 1

Views

Author

Gary W. Adamson, Sep 02 2007

Keywords

Comments

Row sums = A132820: (1, 4, 16, 65, 266, ...).

Examples

			First few rows of the triangle are:
  1;
  1,  3;
  1,  9,   6;
  1, 18,  36,  10;
  1, 30, 120, 100,  15;
  1, 45, 300, 500, 225, 21;
  ...
		

Crossrefs

Formula

A001263 * A127773 as infinite lower triangular matrices.

A136520 a(n) = Sum_{k=1..n} A001263(n,k) * A027656(k).

Original entry on oeis.org

1, 1, 3, 13, 44, 146, 530, 1975, 7314, 27262, 102802, 390138, 1486064, 5682756, 21812436, 83976075, 324115550, 1253795510, 4859960402, 18871869302, 73398851448, 285882923196, 1114943553308, 4353426835238, 17016813133124, 66581653586476, 260750813149140, 1022023318047220
Offset: 1

Views

Author

Gary W. Adamson, Jan 02 2008

Keywords

Comments

Narayana transform of A027656.

Examples

			a(4) = 13 = (1, 6, 6, 1) dot (1, 0, 2, 0) = (1 + 0 + 12 + 0).
Triangle A001263(n,k) * A027656(k+1) and the rows sums:
  1;                                              :     1;
  1,  0;                                          :     1;
  1,  0,    2;                                    :     3;
  1,  0,   12,  0;                                :    13;
  1,  0,   40,  0,     3;                         :    44;
  1,  0,  100,  0,    45,  0;                     :   146;
  1,  0,  210,  0,   315,  0,     4;              :   530;
  1,  0,  392,  0,  1470,  0,   112,  0;          :  1975;
  1,  0,  672,  0,  5292,  0,  1344,  0,    5;    :  7314;
  1,  0, 1080,  0, 15876,  0, 10080,  0,  225,  0 : 27262;
		

Crossrefs

Programs

  • Magma
    A136520:= func< n | (&+[((j+1)/(2*j+1))*Binomial(n,2*j)*Binomial(n-1,2*j): j in [0..Floor((n-1)/2)]]) >;
    [A136520(n): n in [1..40]]; // G. C. Greubel, Jul 27 2023
    
  • Mathematica
    A136520[n_]:= Sum[Binomial[n-1, 2*k]*Binomial[n, 2*k]*((k+1)/(2*k+1)), {k,0,Floor[(n-1)/2]}];
    Table[A136520[n], {n, 40}] (* G. C. Greubel, Jul 27 2023 *)
  • SageMath
    def A136520(n): return sum(((j+1)/(2*j+1))*binomial(n,2*j)*binomial(n-1, 2*j) for j in range((n+1)//2))
    [A136520(n) for n in range(1,41)] # G. C. Greubel, Jul 27 2023

Formula

a(n) = Sum_{k=1..n} A001263(n,k) * A027656(k).
a(n) = Sum_{j=0..floor((n-1)/2)} ((j+1)/(2*j+1))*binomial(n, 2*j) * binomial(n-1, 2*j). - G. C. Greubel, Jul 27 2023

Extensions

Terms a(11) onward added by G. C. Greubel, Jul 27 2023

A136534 A001263 * A128064 (unsigned).

Original entry on oeis.org

1, 2, 2, 4, 8, 3, 7, 24, 21, 4, 11, 60, 90, 44, 5, 16, 130, 300, 260, 80, 6, 22, 2252, 840, 1120, 630, 132, 7, 29, 448, 2058, 3920, 3430, 1344, 203, 8, 37, 744, 4536, 11760, 14700, 9072, 2604, 296, 9, 46, 1170, 9180, 31248, 52920, 46872, 21420, 4680, 414, 10
Offset: 1

Views

Author

Gary W. Adamson, Jan 04 2008

Keywords

Comments

Row sums = A001791: (1, 4, 15, 56, 210, ...).
Left column = A000124: (1, 2, 4, 7, 11, 16, 22, ...).

Examples

			First few rows of the triangle:
   1;
   2,   2;
   4,   8,   3;
   7,  24,  21,    4;
  11,  60,  90,   44,   5;
  16, 130, 300,  260,  80,   6;
  22, 252, 840, 1120, 630, 132, 7;
  ...
		

Crossrefs

Formula

A001263 * A128064 (unsigned), A001263 = the Narayana triangle, A128064 = an infinite lower triangular matrix with (1, 2, 3, ...) in the main and subdiagonals.

A136535 A128064 * A001263.

Original entry on oeis.org

1, 1, 2, 1, 7, 3, 1, 15, 21, 4, 1, 26, 76, 46, 5, 1, 40, 200, 250, 85, 6, 1, 57, 435, 925, 645, 141, 7, 1, 77, 833, 2695, 3185, 1421, 217, 8, 1, 100, 1456, 6664, 11956, 9016, 2800, 316, 9, 1, 126, 2376, 14616, 37044, 42336, 22176, 5076, 441, 10
Offset: 1

Views

Author

Gary W. Adamson, Jan 04 2008

Keywords

Comments

Row sums give A076540.

Examples

			First few rows of the triangle are:
1;
1, 2;
1, 7, 3;
1, 15, 21, 4;
1, 26, 76, 46, 5;
1, 40, 200, 250, 85, 6;
1, 57, 435, 925, 645, 141, 7;
...
		

Crossrefs

Programs

  • PARI
    T4(n,k) = sum(j=k, n, binomial(n,j)*binomial(j,k)*(-1)^(j-k)*(j+1));
    T3(n,k) = binomial(n, k)*binomial(n-1, k-1) - binomial(n, k-1)*binomial(n-1, k);
    N=10; matrix(N, N, n, k, T4(n-1,k-1))*matrix(N, N,n,k,T3(n,k)) \\ Michel Marcus, Oct 11 2021

Extensions

a(18) corrected by Georg Fischer, Oct 10 2021

A143778 Eigentriangle of A001263, the Narayana triangle.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 6, 12, 6, 1, 10, 40, 60, 25, 1, 15, 100, 300, 375, 136, 1, 21, 210, 1050, 2625, 2856, 927, 1, 18, 392, 2940, 12250, 26656, 25956, 7690, 1, 36, 672, 7056, 44100, 15993, 311472, 276840, 75913
Offset: 0

Views

Author

Gary W. Adamson, Aug 31 2008

Keywords

Comments

The Narayana triangle begins:
1;
1, 1;
1, 3, 1;
1, 6, 6, 1;
1, 10, 20, 10, 1;
...
An eigentriangle of T is generated by taking the termwise product of (n-1)-th row terms of triangle T (in this case the Narayana triangle A001263); and the eigensequence of T = A102812 = (1, 1, 2, 6, 25, 136, 927,...).
Sum of n-th row terms of triangle A143778 = rightmost term of (n+1)-th row.
Right border of the triangle = the eigensequence of T.
Row sums of the triangle = the eigensequence of T shifted one place to the left: (1, 2, 6, 25, 136,...)
(A102812 * 0^(n-k)) = an infinite lower triangular matrix with A102812 as the main diagonal and the rest zeros.

Examples

			Triangle begins:
1;
1, 1;
1, 3, 2;
1, 6, 12, 6;
1, 10, 40, 60, 25;
1, 15, 100, 300, 375, 136;
1, 21, 210, 1050, 2625, 2856, 927;
...
Row 3 = (1, 6, 12, 6) = (1*1, 6*1, 6*2, 1*6) = termwise product of row 3 of the Narayana triangle: (1, 6, 6, 1) and the first 4 terms of the eigensequence of the Narayana triangle = (1, 1, 2, 6).
		

Crossrefs

Formula

Triangle read by rows, A001263 * (A102812 * 0^(n-k)); 0<=k<=n
Apparently for kTom Copeland, Oct 08 2014

A155537 Triangle T(n,k,p,q) = (p^n + q^n)*A001263(n, k) with p=2 and q=1, read by rows.

Original entry on oeis.org

3, 5, 5, 9, 27, 9, 17, 102, 102, 17, 33, 330, 660, 330, 33, 65, 975, 3250, 3250, 975, 65, 129, 2709, 13545, 22575, 13545, 2709, 129, 257, 7196, 50372, 125930, 125930, 50372, 7196, 257, 513, 18468, 172368, 603288, 904932, 603288, 172368, 18468, 513
Offset: 1

Views

Author

Roger L. Bagula, Jan 23 2009

Keywords

Examples

			Triangle begins as:
     3;
     5,     5;
     9,    27,      9;
    17,   102,    102,      17;
    33,   330,    660,     330,      33;
    65,   975,   3250,    3250,     975,      65;
   129,  2709,  13545,   22575,   13545,    2709,     129;
   257,  7196,  50372,  125930,  125930,   50372,    7196,    257;
   513, 18468, 172368,  603288,  904932,  603288,  172368,  18468,   513;
  1025, 46125, 553500, 2583000, 5424300, 5424300, 2583000, 553500, 46125, 1025;
		

Crossrefs

Programs

  • Magma
    T:= func< n,k,p,q | (p^n + q^n)*Binomial(n-1, k-1)*Binomial(n, k)/(n-k+1) >;
    [T(n,k,2,1): k in [1..n], n in [1..12]]; // G. C. Greubel, Mar 15 2021
  • Maple
    A155537:= (n,k,p,q)-> (p^n + q^n)*binomial(n-1, k-1)*binomial(n, k)/(n-k+1);
    seq(seq(A155537(n,k,2,1), k=1..n), n=1..12); # G. C. Greubel, Mar 15 2021
  • Mathematica
    T[n_, k_, p_, q_]:= T[n,k,p,q]= (p^n + q^n)*Binomial[n-1, k-1]*Binomial[n, k]/(n-k+1);
    Table[T[n,k,2,1], {n, 12}, {k, n}]//Flatten (* modified by G. C. Greubel, Mar 15 2021 *)
  • Sage
    def T(n,k,p,q): return (p^n + q^n)*binomial(n-1, k-1)*binomial(n, k)/(n-k+1)
    flatten([[T(n,k,2,1) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Mar 15 2021
    

Formula

Define T(n,k,p,q) = (p^n + q^n)*binomial(n-1, k-1)*binomial(n, k)/(n-k+1) (A scaled Narayana triangle) for various p and q. When p = 2 and q = 1 this sequence is obtained.
From G. C. Greubel, Mar 15 2021: (Start)
T(n,k,p,q) = T(n,k,q,p) = (p^n + q^n)*A001263(n, k).
T(n,k,2,1) = A000051(n) * A001263(n,k).
Sum_{k=1..n} T(n,k,p,q) = (p^n + q^n)*C(n), where C(n) are the Catalan numbers (A000108). (End)

Extensions

Edited by G. C. Greubel, Mar 15 2021

A157243 Triangle T(n, k) = A001263(n*f(n,k) + 1, f(n,k) + 1), where f(n, k) = k if k <= floor(n/2) otherwise n-k, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 6, 6, 1, 1, 10, 336, 10, 1, 1, 15, 825, 825, 15, 1, 1, 21, 1716, 197676, 1716, 21, 1, 1, 28, 3185, 512050, 512050, 3185, 28, 1, 1, 36, 5440, 1163800, 294296640, 1163800, 5440, 36, 1, 1, 45, 8721, 2395575, 778076145, 778076145, 2395575, 8721, 45, 1
Offset: 0

Views

Author

Roger L. Bagula, Feb 25 2009

Keywords

Examples

			Triangle begins as:
  1;
  1,  1;
  1,  3,    1;
  1,  6,    6,       1;
  1, 10,  336,      10,         1;
  1, 15,  825,     825,        15,         1;
  1, 21, 1716,  197676,      1716,        21,       1;
  1, 28, 3185,  512050,    512050,      3185,      28,    1;
  1, 36, 5440, 1163800, 294296640,   1163800,    5440,   36,  1;
  1, 45, 8721, 2395575, 778076145, 778076145, 2395575, 8721, 45, 1;
		

Crossrefs

Programs

  • Magma
    f:= func< n,k | k le Floor(n/2) select k else n-k >;
    A001263:= func< n,k | Binomial(n-1,k-1)*Binomial(n,k)/(n-k+1) >;
    [A001263(n*f(n,k)+1, f(n,k)+1): k in [0..n], n in [0..12]]; // G. C. Greubel, Jan 11 2022
    
  • Mathematica
    f[n_, k_]:= If[k<=Floor[n/2], k, n-k];
    A001263[n_, k_]:= Binomial[n-1,k-1]*Binomial[n,k]/(n-k+1);
    T[n_, k_]:= A001263[n*f[n,k] +1, f[n,k] +1];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* modified by G. C. Greubel, Jan 11 2022 *)
  • Sage
    def f(n,k): return k if (k <= (n//2)) else n-k
    def A001263(n,k): return binomial(n-1,k-1)*binomial(n,k)/(n-k+1)
    flatten([[A001263(n*f(n,k)+1, f(n,k)+1) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Jan 11 2022

Formula

T(n, k) = A001263(n*f(n,k) + 1, f(n,k) + 1), where f(n, k) = k if k <= floor(n/2) otherwise n-k.
T(n, n-k) = T(n, k).
T(n, 1) = A000217(n). - G. C. Greubel, Jan 11 2022

Extensions

Edited by G. C. Greubel, Jan 11 2022

A168391 Triangle T(n, k) = [x^k]( p(n,x) ), where p(n, x) = Sum_{k=1..n} A001263(n,k)*binomial(x+k -1, n-1), read by rows.

Original entry on oeis.org

1, 1, 2, 2, 5, 5, 6, 19, 21, 14, 24, 84, 126, 84, 42, 120, 468, 750, 720, 330, 132, 720, 2988, 5496, 5445, 3795, 1287, 429, 5040, 22356, 43120, 50435, 35035, 19019, 5005, 1430, 40320, 186912, 391688, 472472, 398398, 208208, 92092, 19448, 4862
Offset: 1

Views

Author

Roger L. Bagula, Nov 24 2009

Keywords

Comments

The Z-transform of the triangle gives the Narayan triangle (A001263).
Every other polynomial, of p(n, x), has a factor of (1+2*x), just like the higher Sierpinski-Pascal Worpitzky form polynomials.

Examples

			Triangle begins as:
      1;
      1,      2;
      2,      5,      5;
      6,     19,     21,     14;
     24,     84,    126,     84,     42;
    120,    468,    750,    720,    330,    132;
    720,   2988,   5496,   5445,   3795,   1287,   429;
   5040,  22356,  43120,  50435,  35035,  19019,  5005,  1430;
  40320, 186912, 391688, 472472, 398398, 208208, 92092, 19448, 4862;
		

Crossrefs

Programs

  • Mathematica
    p[n_, x_]:= p[n,x]= ((-1)^(n+1)/(n+1))*Sum[Binomial[n-1, k-1]*Binomial[n+1, k]*Pochhammer[1-k-x, n-1], {k, n}];
    A168391[n_]:= CoefficientList[p[x, n], x];
    Table[A168391[n], {n,12}]//Flatten (* G. C. Greubel, Mar 28 2022 *)
  • Sage
    @CachedFunction
    def p(n,x): return ((-1)^(n+1)/(n+1))*sum( binomial(n+1, k)*binomial(n-1, k-1)*rising_factorial(1-k-x, n-1) for k in (1..n) )
    def A168391(n,k): return ( p(n,x) ).series(x, n+1).list()[k]
    flatten([[A168391(n,k) for k in (0..n-1)] for n in (1..12)]) # G. C. Greubel, Mar 28 2022

Formula

T(n, k) = [x^k]( p(n,x) ), where p(n, x) = Sum_{k=1..n} A001263(n,k)*binomial(x+k -1, n-1).
From G. C. Greubel, Mar 28 2022: (Start)
Sum_{k=0..n-1} T(n, k) = A001710(n+1).
T(n, 0) = n!. (End)

Extensions

Edited by G. C. Greubel, Mar 28 2022

A178655 Triangle which contains the first differences of the Catalan triangle A001263 constructed along rows.

Original entry on oeis.org

1, 1, -1, 1, 0, -1, 1, 2, -2, -1, 1, 5, 0, -5, -1, 1, 9, 10, -10, -9, -1, 1, 14, 35, 0, -35, -14, -1, 1, 20, 84, 70, -70, -84, -20, -1, 1, 27, 168, 294, 0, -294, -168, -27, -1, 1, 35, 300, 840, 588, -588, -840, -300, -35, -1
Offset: 0

Views

Author

Roger L. Bagula, Jun 01 2010

Keywords

Examples

			Triangle begins
  1;
  1,   -1;
  1,    0,   -1;
  1,    2,   -2,   -1;
  1,    5,    0,   -5,   -1;
  1,    9,   10,  -10,   -9,   -1;
  1,   14,   35,    0,  -35,  -14,   -1;
  1,   20,   84,   70,  -70,  -84,  -20,   -1;
  1,   27,  168,  294,    0, -294, -168,  -27,   -1;
  1,   35,  300,  840,  588, -588, -840, -300,  -35,   -1;
		

Crossrefs

Cf. A001263, A000007 (row sums).

Programs

  • Magma
    [[n le 0 select 1 else ((n+1)*(n-2*k)/(n*(k+1)*(n-k+1)))*Binomial(n, k)^2: k in [0..n]]: n in [0..10]]; // G. C. Greubel, Jan 28 2019
    
  • Mathematica
    Join[{1}, Table[((n+1)*(n-2*k)/(n*(k+1)*(n-k+1)))*Binomial[n, k]^2, {n, 1, 10}, {k, 0, n}]//Flatten] (* G. C. Greubel, Jan 28 2019 *)
  • PARI
    {T(n,k) = if(n==0, 1, ((n+1)*(n-2*k)/(n*(k+1)*(n-k+1)))* binomial(n, k)^2)};
    for(n=0,10, for(k=0,n, print1(T(n,k), ", "))) \\ G. C. Greubel, Jan 28 2019
    
  • Sage
    [1] + [[((n+1)*(n-2*k)/(n*(k+1)*(n-k+1)))* binomial(n, k)^2 for k in (0..n)] for n in (1..10)] # G. C. Greubel, Jan 28 2019

Formula

T(n,k) = -T(n,n-k), n > 0.
T(n,k) = A001263(n,k+1) - A001263(n,k), n > 0. - R. J. Mathar, Jun 16 2015
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