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 1-6 of 6 results.

A008550 Table T(n,k), n>=0 and k>=0, read by antidiagonals: the k-th column given by the k-th Narayana polynomial.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 5, 3, 1, 1, 1, 14, 11, 4, 1, 1, 1, 42, 45, 19, 5, 1, 1, 1, 132, 197, 100, 29, 6, 1, 1, 1, 429, 903, 562, 185, 41, 7, 1, 1, 1, 1430, 4279, 3304, 1257, 306, 55, 8, 1, 1, 1, 4862, 20793, 20071, 8925, 2426, 469, 71, 9, 1, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 23 2004

Keywords

Comments

Mirror image of A243631. - Philippe Deléham, Sep 26 2014

Examples

			Row n=0:  1, 1,  1,   1,    1,     1,      1, ... see A000012.
Row n=1:  1, 1,  2,   5,   14,    42,    132, ... see A000108.
Row n=2:  1, 1,  3,  11,   45,   197,    903, ... see A001003.
Row n=3:  1, 1,  4,  19,  100,   562,   3304, ... see A007564.
Row n=4:  1, 1,  5,  29,  185,  1257,   8925, ... see A059231.
Row n=5:  1, 1,  6,  41,  306,  2426,  20076, ... see A078009.
Row n=6:  1, 1,  7,  55,  469,  4237,  39907, ... see A078018.
Row n=7:  1, 1,  8,  71,  680,  6882,  72528, ... see A081178.
Row n=8:  1, 1,  9,  89,  945, 10577, 123129, ... see A082147.
Row n=9:  1, 1, 10, 109, 1270, 15562, 198100, ... see A082181.
Row n=10: 1, 1, 11, 131,  161,  1661,  22101, ... see A082148.
Row n=11: 1, 1, 12, 155, 2124, 30482, 453432, ... see A082173.
... - _Philippe Deléham_, Apr 03 2013
The first few rows of the antidiagonal triangle are:
  1;
  1,  1;
  1,  1,  1;
  1,  2,  1,  1;
  1,  5,  3,  1, 1;
  1, 14, 11,  4, 1, 1;
  1, 42, 45, 19, 5, 1, 1; - _G. C. Greubel_, Feb 15 2021
		

Crossrefs

Main diagonal is A242369.
A diagonal is in A099169.
Cf. A204057 (another version), A088617, A243631.
Cf. A132745.

Programs

  • Magma
    [Truncate(HypergeometricSeries(k-n, k-n+1, 2, k)): k in [0..n], n in [0..12]]; // G. C. Greubel, Feb 15 2021
  • Maple
    gf := n -> 2/(sqrt((n-1)^2*x^2-2*(n+1)*x+1)+(n-1)*x+1):
    for n from 0 to 11 do PolynomialTools:-CoefficientList(convert( series(gf(n),x,12),polynom),x) od; # Peter Luschny, Nov 17 2014
  • Mathematica
    (* First program *)
    Unprotect[Power]; Power[0 | 0, 0 | 0] = 1; Protect[Power]; Table[Function[n, Sum[Apply[Binomial[#1 + #2, #1] Binomial[#1, #2]/(#2 + 1) &, {k, j}]*n^j*(1 - n)^(k - j), {j, 0, k}]][m - k + 1] /. k_ /; k <= 0 -> 1, {m, -1, 9}, {k, m + 1, 0, -1}] // Flatten (* Michael De Vlieger, Aug 10 2017 Note: this code renders 0^0 = 1. To restore normal Power functionality: Unprotect[Power]; ClearAll[Power]; Protect[Power] *)
    (* Second program *)
    Table[Hypergeometric2F1[1-n+k, k-n, 2, k], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Feb 15 2021 *)
  • Sage
    flatten([[hypergeometric([k-n, k-n+1], [2], k).simplify_hypergeometric() for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 15 2021
    

Formula

T(n, k) = Sum_{j>0} A001263(k, j)*n^(j-1); T(n, 0)=1.
T(n, k) = Sum_{j, 0<=j<=k} A088617(k, j)*n^j*(1-n)^(k-j).
The o.g.f. of row n is gf(n) = 2/(sqrt((n-1)^2*x^2-2*(n+1)*x+1)+(n-1)*x+1). - Peter Luschny, Nov 17 2014
G.f. of row n: 1/(1 - x/(1 - n*x/(1 - x/(1 - n*x/(1 - x/(1 - ...)))))), a continued fraction. - Ilya Gutkovskiy, Aug 10 2017
T(n, k) = Hypergeometric2F1([k-n, k-n+1], [2], k), as a number triangle. - G. C. Greubel, Feb 15 2021

A243631 Square array of Narayana polynomials N_n evaluated at the integers, A(n,k) = N_n(k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 5, 1, 1, 1, 4, 11, 14, 1, 1, 1, 5, 19, 45, 42, 1, 1, 1, 6, 29, 100, 197, 132, 1, 1, 1, 7, 41, 185, 562, 903, 429, 1, 1, 1, 8, 55, 306, 1257, 3304, 4279, 1430, 1, 1, 1, 9, 71, 469, 2426, 8925, 20071, 20793, 4862, 1
Offset: 0

Views

Author

Peter Luschny, Jun 08 2014

Keywords

Comments

Mirror image of A008550. - Philippe Deléham, Sep 26 2014

Examples

			   [0]  [1]      [2]      [3]      [4]      [5]      [6]     [7]
[0] 1,   1,       1,       1,       1,       1,       1,       1
[1] 1,   1,       1,       1,       1,       1,       1,       1
[2] 1,   2,       3,       4,       5,       6,       7,       8 .. A000027
[3] 1,   5,      11,      19,      29,      41,      55,      71 .. A028387
[4] 1,  14,      45,     100,     185,     306,     469,     680 .. A090197
[5] 1,  42,     197,     562,    1257,    2426,    4237,    6882 .. A090198
[6] 1, 132,     903,    3304,    8925,   20076,   39907,   72528 .. A090199
[7] 1, 429,    4279,   20071,   65445,  171481,  387739,  788019 .. A090200
   A000108, A001003, A007564, A059231, A078009, A078018, A081178
First few rows of the antidiagonal triangle are:
  1;
  1, 1;
  1, 1, 1;
  1, 1, 2,  1;
  1, 1, 3,  5,  1;
  1, 1, 4, 11, 14,  1;
  1, 1, 5, 19, 45, 42, 1; - _G. C. Greubel_, Feb 16 2021
		

Crossrefs

Cf. A001263, A008550 (mirror), A204057 (another version), A242369 (main diagonal), A099169 (diagonal), A307883, A336727.
Cf. A132745.

Programs

  • Magma
    A243631:= func< n,k | n eq 0 select 1 else (&+[ Binomial(n,j)^2*k^j*(n-j)/(n*(j+1)): j in [0..n-1]]) >;
    [A243631(k,n-k): k in [0..n], n in [0..12]]; // G. C. Greubel, Feb 16 2021
  • Maple
    # Computed with Narayana polynomials:
    N := (n,k) -> binomial(n,k)^2*(n-k)/(n*(k+1));
    A := (n,x) -> `if`(n=0, 1, add(N(n,k)*x^k, k=0..n-1));
    seq(print(seq(A(n,k), k=0..7)), n=0..7);
    # Computed by recurrence:
    Prec := proc(n,N,k) option remember; local A,B,C,h;
    if n = 0 then 1 elif n = 1 then 1+N+(1-N)*(1-2*k)
    else h := 2*N-n; A := n*h*(1+N-n); C := n*(h+2)*(N-n);
    B := (1+h-n)*(n*(1-2*k)*(1+h)+2*k*N*(1+N));
    (B*Prec(n-1,N,k) - C*Prec(n-2,N,k))/A fi end:
    T := (n, k) -> Prec(n,n,k)/(n+1);
    seq(print(seq(T(n,k), k=0..7)), n=0..7);
    # Array by o.g.f. of columns:
    gf := n -> 2/(sqrt((n-1)^2*x^2-2*(n+1)*x+1)+(n-1)*x+1):
    for n from 0 to 11 do PolynomialTools:-CoefficientList(convert( series(gf(n), x, 12), polynom), x) od; # Peter Luschny, Nov 17 2014
    # Row n by linear recurrence:
    rec := n -> a(x) = add((-1)^(k+1)*binomial(n,k)*a(x-k), k=1..n):
    ini := n -> seq(a(k) = A(n,k), k=0..n): # for A see above
    row := n -> gfun:-rectoproc({rec(n),ini(n)},a(x),list):
    for n from 1 to 7 do row(n)(8) od; # Peter Luschny, Nov 19 2014
  • Mathematica
    MatrixForm[Table[JacobiP[n,1,-2*n-1,1-2*x]/(n+1), {n,0,7},{x,0,7}]]
    Table[Hypergeometric2F1[1-k, -k, 2, n-k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Feb 16 2021 *)
  • Sage
    def NarayanaPolynomial():
        R = PolynomialRing(ZZ, 'x')
        D = [1]
        h = 0
        b = True
        while True:
            if b :
                for k in range(h, 0, -1):
                    D[k] += x*D[k-1]
                h += 1
                yield R(expand(D[0]))
                D.append(0)
            else :
                for k in range(0, h, 1):
                    D[k] += D[k+1]
            b = not b
    NP = NarayanaPolynomial()
    for _ in range(8):
        p = next(NP)
        [p(k) for k in range(8)]
    
  • Sage
    def A243631(n,k): return 1 if n==0 else sum( binomial(n,j)^2*k^j*(n-j)/(n*(j+1)) for j in [0..n-1])
    flatten([[A243631(k,n-k) for k in [0..n]] for n in [0..12]]) # G. C. Greubel, Feb 16 2021
    

Formula

T(n, k) = 2F1([1-n, -n], [2], k), 2F1 the hypergeometric function.
T(n, k) = P(n,1,-2*n-1,1-2*k)/(n+1), P the Jacobi polynomials.
T(n, k) = sum(j=0..n-1, binomial(n,j)^2*(n-j)/(n*(j+1))*k^j), for n>0.
For a recurrence see the second Maple program.
The o.g.f. of column n is gf(n) = 2/(sqrt((n-1)^2*x^2-2*(n+1)*x+1)+(n-1)*x+1). - Peter Luschny, Nov 17 2014
T(n, k) ~ (sqrt(k)+1)^(2*n+1)/(2*sqrt(Pi)*k^(3/4)*n^(3/2)). - Peter Luschny, Nov 17 2014
The n-th row can for n>=1 be computed by a linear recurrence, a(x) = sum(k=1..n, (-1)^(k+1)*binomial(n,k)*a(x-k)) with initial values a(k) = p(n,k) for k=0..n and p(n,x) = sum(j=0..n-1, binomial(n-1,j)*binomial(n,j)*x^j/(j+1)) (implemented in the fourth Maple script). - Peter Luschny, Nov 19 2014
(n+1) * T(n,k) = (k+1) * (2*n-1) * T(n-1,k) - (k-1)^2 * (n-2) * T(n-2,k) for n>1. - Seiichi Manyama, Aug 08 2020
Sum_{k=0..n} T(k, n-k) = Sum_{k=0..n} 2F1([-k, 1-k], [2], n-k) = A132745(n). - G. C. Greubel, Feb 16 2021

A090198 a(n) = N(5,n), where N(5,x) is the 5th Narayana polynomial.

Original entry on oeis.org

1, 42, 197, 562, 1257, 2426, 4237, 6882, 10577, 15562, 22101, 30482, 41017, 54042, 69917, 89026, 111777, 138602, 169957, 206322, 248201, 296122, 350637, 412322, 481777, 559626, 646517, 743122, 850137, 968282, 1098301, 1240962, 1397057
Offset: 0

Views

Author

Philippe Deléham, Jan 22 2004

Keywords

Crossrefs

Programs

Formula

a(n) = N(5, n) = Sum_{k>0} A001263(5, k)*n^(k-1) = n^4 +10*n^3 +20*n^2 +10*n +1.
G.f.: (1 +37*x -3*x^2 -13*x^3 +2*x^4)/(1-x)^5. - Philippe Deléham, Apr 03 2013
E.g.f.: (1 +41*x +57*x^2 +16*x^3 +x^4)*exp(x). - G. C. Greubel, Feb 16 2021

Extensions

Corrected by T. D. Noe, Nov 08 2006

A090199 a(n) = N(6,n), where N(6,x) is the 6th Narayana polynomial.

Original entry on oeis.org

1, 132, 903, 3304, 8925, 20076, 39907, 72528, 123129, 198100, 305151, 453432, 653653, 918204, 1261275, 1698976, 2249457, 2933028, 3772279, 4792200, 6020301, 7486732, 9224403, 11269104, 13659625, 16437876, 19649007, 23341528, 27567429
Offset: 0

Views

Author

Philippe Deléham, Jan 22 2004

Keywords

Crossrefs

Programs

  • Magma
    [(n+1)*(n^4 +14*n^3 +36*n^2 +14*n +1): n in [0..30]]; // G. C. Greubel, Feb 16 2021
  • Mathematica
    Table[(n+1)*(n^4 +14*n^3 +36*n^2 +14*n +1), {n,0,30}] (* G. C. Greubel, Feb 16 2021 *)
    LinearRecurrence[{6,-15,20,-15,6,-1},{1,132,903,3304,8925,20076},30] (* or *) CoefficientList[Series[(1+126 x+126 x^2-154 x^3+21 x^4)/(-1+x)^6,{x,0,30}],x] (* Harvey P. Dale, Jul 24 2021 *)
  • PARI
    a(n)=n^5+15*n^4+50*n^3+50*n^2+15*n+1 \\ Charles R Greathouse IV, Jan 17 2012
    
  • Sage
    [(n+1)*(n^4 +14*n^3 +36*n^2 +14*n +1) for n in (0..30)] # G. C. Greubel, Feb 16 2021
    

Formula

a(n) = N(6, n)= Sum_{k>0} A001263(6, k)*n^(k-1) = n^5 + 15*n^4 + 50*n^3 + 50*n^2 + 15*n + 1.
G.f.: (1 +126*x +126*x^2 -154*x^3 +21*x^4)/(1-x)^6. - Philippe Deléham, Apr 03 2013
E.g.f.: (1 +131*x +320*x^2 +165*x^3 +25*x^4 +x^5)*exp(x). - G. C. Greubel, Feb 16 2021

Extensions

Corrected generating function in Formula field. - Harvey P. Dale, Jul 24 2021

A204057 Triangle derived from an array of f(x), Narayana polynomials.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 5, 1, 1, 4, 11, 14, 1, 1, 5, 19, 45, 42, 1, 1, 6, 29, 100, 197, 132, 1, 1, 7, 41, 185, 562, 903, 429, 1, 1, 8, 55, 306, 1257, 3304, 4279, 1430, 1, 1, 9, 71, 469, 2426, 8925, 20071, 20793, 4862, 1, 1, 10, 89, 680, 4237, 20076, 65445, 124996, 103049, 16796, 1
Offset: 1

Views

Author

Gary W. Adamson, Jan 09 2012

Keywords

Comments

Row sums = (1, 2, 4, 10, 31, 113, 466, 2129, 10641, 138628, 335379, 2702364,...)
Another version of triangle in A008550. - Philippe Deléham, Jan 13 2012
Another version of A243631. - Philippe Deléham, Sep 26 2014

Examples

			First few rows of the array =
  1,....1,....1,.....1,.....1,...; = A000012
  1.....2,....5,....14,....42,...; = A000108
  1,....3,...11,....45,...197,...; = A001003
  1,....4,...19,...100,...562,...; = A007564
  1,....5,...29,...185,..1257,...; = A059231
  1,....6,...41,...306,..2426,...; = A078009
  ...
First few rows of the triangle =
  1;
  1, 1;
  1, 2,  1;
  1, 3,  5,   1;
  1, 4, 11,  14,    1;
  1, 5, 19,  45,   42,    1;
  1, 6, 29, 100,  197,  132,     1;
  1, 7, 41, 185,  562,  903,   429,     1;
  1, 8, 55, 306, 1257, 3304,  4279,  1430,    1;
  1, 9, 71, 469, 2426, 8952, 20071, 20793, 4862, 1;
  ...
Examples: column 4 of the array = A090197: (1, 14, 45, 100,...) = N(4,n) where N(4,x) is the 4th Narayana polynomial.
Term (5,3) = 29 is the upper left term of M^3, where M = the infinite square production matrix:
  1, 4, 0, 0, 0,...
  1, 1, 4, 0, 0,...
  1, 1, 1, 4, 0,...
  1, 1, 1, 1, 4,...
... generating row 5, A059231: (1, 5, 29, 185,...).
		

Crossrefs

Programs

  • Magma
    A204057:= func< n, k | n eq 0 select 1 else (&+[ Binomial(n, j)^2*k^j*(n-j)/(n*(j+1)): j in [0..n-1]]) >;
    [A204057(k, n-k): k in [1..n], n in [1..12]]; // G. C. Greubel, Feb 16 2021
  • Mathematica
    Table[Hypergeometric2F1[1-k, -k, 2, n-k], {n,12}, {k,n}]//Flatten (* G. C. Greubel, Feb 16 2021 *)
  • Sage
    def A204057(n, k): return 1 if n==0 else sum( binomial(n, j)^2*k^j*(n-j)/(n*(j+1)) for j in [0..n-1])
    flatten([[A204057(k, n-k) for k in [1..n]] for n in [1..12]]) # G. C. Greubel, Feb 16 2021
    

Formula

The triangle is the set of antidiagonals of an array in which columns are f(x) of the Narayana polynomials; with column 1 = (1, 1, 1,...) column 2 = (1, 2, 3,..), column 3 = A028387, column 4 = A090197, then A090198, A090199,...
The array by rows is generated from production matrices of the form:
1, (N-1)
1, 1, (N-1)
1, 1, 1, (N-1)
1, 1, 1, 1, (N-1)
...(infinite square matrices with the rest zeros); such that if the matrix is M, n-th term in row N is the upper left term of M^n.
From G. C. Greubel, Feb 16 2021: (Start)
T(n, k) = Hypergeometric2F1([1-k, -k], [2], n-k).
Sum_{k=1..n} T(n, k) = A132745(n) - 1. (End)

Extensions

Corrected by Philippe Deléham, Jan 13 2012

A247502 Triangle read by rows: coefficients of polynomials related to the exponential generating function of sequences generated by Narayana polynomials evaluated at the integers; n>=1, 0<=k

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 13, 9, 1, 1, 41, 57, 16, 1, 1, 131, 320, 165, 25, 1, 1, 428, 1711, 1420, 380, 36, 1, 1, 1429, 8967, 11151, 4620, 756, 49, 1, 1, 4861, 46663, 83202, 49665, 12306, 1358, 64, 1, 1, 16795, 242634, 602407, 495327, 172893, 28476, 2262, 81, 1
Offset: 1

Views

Author

Peter Luschny, Nov 18 2014

Keywords

Comments

Definition: Let N(n,x) = Sum_{j=0..n-1} x^j*C(n,j)^2*(n-j)/(n*(j+1)) for n>0 and N(0,x) = 1, further let p(n,x) be implicitly defined by N(n,k) = k!*[x^k](exp(x)*p(n,x)), then T(n,k) = [x^k] p(n,x).

Examples

			Triangle T(n,k) begins:
[n\k][0,    1,     2,     3,     4,     5,    6,  8, 9]
[1]   1,
[2]   1,    1,
[3]   1,    4,     1,
[4]   1,   13,     9,     1,
[5]   1,   41,    57,    16,     1,
[6]   1,  131,   320,   165,    25,     1,
[7]   1,  428,  1711,  1420,   380,    36,    1,
[8]   1, 1429,  8967, 11151,  4620,   756,   49,  1,
[9]   1, 4861, 46663, 83202, 49665, 12306, 1358, 64, 1.
.
The sequence N(7,k) = 1 + 21*k + 105*k^2 + 175*k^3 + 105*k^4 + 21*k^5 + k^6 = 1, 429, 4279, 20071, 65445, ... = A090200(k) has the exponential generating function exp(x)*(1 + 428*x + 1711*x^2 + 1420*x^3 + 380*x^4 + 36*x^5 + x^6). Thus T(7,3) = 1420.
		

Crossrefs

Cf. A243631 and the crossreferences given there.

Formula

T(n, 0) = T(n, n-1) = 1.
T(n, 1) = A001453(n) = A000108(n) - 1 for n>=2.
T(n, n-2) = (n-1)^2 for n>=2.
Showing 1-6 of 6 results.