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 10 results.

A228329 a(n) = Sum_{k=0..n} (k+1)^2*T(n,k)^2 where T(n,k) is the Catalan triangle A039598.

Original entry on oeis.org

1, 8, 98, 1320, 18590, 268736, 3952228, 58837680, 883941750, 13373883600, 203487733020, 3110407163760, 47726453450988, 734694122886080, 11341161925265480, 175489379096245984, 2721169178975361702, 42273090191785999728, 657788911222324942060, 10250564041646388681200
Offset: 0

Views

Author

N. J. A. Sloane, Aug 26 2013

Keywords

Comments

Let h(m) denote the sequence whose n-th term is Sum_{k=0..n} (k+1)^m*T(n,k)^2, where T(n,k) is the Catalan triangle A039598. This is h(2).

Crossrefs

Cf. A039598, A000108, A024492 (h(0)), A000894 (h(1)), A000515 (h(3)), A228330 (h(4)), A228331 (h(5)), A228332 (h(6)), A228333 (h(7)).

Programs

  • Maple
    B:=(n,k)->binomial(2*n, n-k) - binomial(2*n, n-k-2); #A039598
    Omega:=(m,n)->add((k+1)^m*B(n,k)^2,k=0..n);
    h:=m->[seq(Omega(m,n),n=0..20)];
    h(2);
    # Second solution:
    h := n -> I*HeunG(8/5,0,-1/4,1/4,3/2,1/2,16*x)/sqrt(16*x-1);
    seq(coeff(series(h(x),x,n+2),x,n),n=0..19); # Peter Luschny, Nov 26 2013
  • Mathematica
    a[n_] := Binomial[4n, 2n] (3n+1)/(2n+1);
    Table[a[n], {n, 0, 19}] (* Jean-François Alcover, Jul 30 2018, after Philippe Deléham *)
  • Sage
    @CachedFunction
    def A228329(n):
        return A228329(n-1)*(6*n+2)*(4*n-3)*(4*n-1)/(n*(2*n+1)*(3*n-2)) if n>0 else 1
    [A228329(n) for n in (0..19)]  # Peter Luschny, Nov 26 2013

Formula

Conjecture: n*(2*n+1)*a(n) + 2*(-26*n^2+25*n-11)*a(n-1) + 20*(4*n-5)*(4*n-7)*a(n-2) = 0. - R. J. Mathar, Sep 08 2013
a(n) = ((4n)!*(3n+1))/((2n)!^2*(2n+1)) = binomial(4n,2n)*(3n+1)/(2n+1). - Philippe Deléham, Nov 25 2013
Therefore a(n) = A051960(2*n) / 2. - F. Chapoton, Jun 14 2024
From Peter Luschny, Nov 26 2013: (Start)
a(n) = 16^n*(3*n+1)*gamma(2*n+1/2)/(sqrt(Pi)*gamma(2*n+2)).
a(n) = a(n-1)*(6*n+2)*(4*n-3)*(4*n-1)/(n*(2*n+1)*(3*n-2)) if n > 0 else 1.
a(n) = [x^n] I*HeunG(8/5,0,-1/4,1/4,3/2,1/2,16*x)/sqrt(16*x-1) where [x^n] f(x) is the coefficient of x^n in f(x) and HeunG is the Heun general function. (End)

A265612 a(n) = CatalanNumber(n+1)*n*(1+3*n)/(6+2*n).

Original entry on oeis.org

0, 1, 7, 35, 156, 660, 2717, 11011, 44200, 176358, 700910, 2778446, 10994920, 43459650, 171655785, 677688675, 2674776720, 10555815270, 41656918050, 164401379610, 648887951400, 2561511781920, 10113397410402, 39937416869070, 157743149913776, 623178050662300
Offset: 0

Views

Author

Peter Luschny, Dec 15 2015

Keywords

Comments

This is row n=7 in the array A(n,k) = (rf(k+n-2,k-1)-(k-1)*(k-2)*rf(k+n-2, k-3))/ (k-1)! if n>=3 and A(n,0)=0, A(n,1)=1, A(n,2)=n; rf(n,k) denotes the rising factorial. See the cross-references for other values of n and the table in A264357.

Crossrefs

Programs

  • Maple
    A265612 := n -> 2*4^n*GAMMA(3/2+n)*n*(1+3*n)/(sqrt(Pi)*GAMMA(4+n)):
    seq(simplify(A265612(n)), n=0..25);
  • Mathematica
    Table[SeriesCoefficient[(5 x + (I (x - 1) (7 x - 2))/Sqrt[4 x - 1] - 2 - x^2)/(2 x^3), {x, 0, n}], {n, 0, 25}] (* or *)
    Table[2*4^n Gamma[3/2 + n] n (1 + 3 n)/(Sqrt[Pi] Gamma[4 + n]), {n, 0, 25}] (* or *)
    Table[CatalanNumber[n + 1] n ((1 + 3 n)/(6 + 2 n)), {n, 0, 25}] (* Michael De Vlieger, Dec 15 2015 *)
  • PARI
    for(n=0,25, print1(round(2*4^n*gamma(3/2+n)*n*(1+3*n)/(sqrt(Pi)*gamma(4+n))), ", ")) \\ G. C. Greubel, Feb 06 2017
  • Sage
    a = lambda n: catalan_number(n+1)*n*(1+3*n)/(6+2*n)
    [a(n) for n in range(26)]
    

Formula

G.f.: (5*x+(I*(x-1)*(7*x-2))/sqrt(4*x-1)-2-x^2)/(2*x^3).
a(n) = 2*4^n*Gamma(3/2+n)*n*(1+3*n)/(sqrt(Pi)*Gamma(4+n)).
a(n) = (rf(5+n, n-1)-(n-1)*(n-2)*rf(5+n, n-3))/(n-1)! for n>=3, rf(n,k) the rising factorial.
a(n) = a(n-1)*(2*n*(1+3*n)*(1+2*n)/((n-1)*(3*n-2)*(3+n))) for n>=2.
a(n) ~ 4^n*(6-(127/4)/n+(7995/64)/n^2-(223405/512)/n^3+(23501457/16384)/n^4-...) /sqrt(n*Pi).
a(n) = [x^n] x*(1 + x)/(1 - x)^(n+4). - Ilya Gutkovskiy, Oct 09 2017

A146983 a(n) = A002531(n)*A002531(n+1).

Original entry on oeis.org

1, 2, 10, 35, 133, 494, 1846, 6887, 25705, 95930, 358018, 1336139, 4986541, 18610022, 69453550, 259204175, 967363153, 3610248434, 13473630586, 50284273907, 187663465045, 700369586270, 2613814880038, 9754889933879, 36405744855481, 135868089488042
Offset: 0

Views

Author

Paul Barry, Nov 04 2008

Keywords

Comments

a(n+1) is the Hankel transform of A051960 aerated.

Crossrefs

Programs

  • GAP
    a:=[1,2,10];; for n in [4..30] do a[n]:=3*a[n-1]+3*a[n-2]-a[n-3]; od; a; # G. C. Greubel, Jan 09 2020
  • Magma
    R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (1-x+x^2)/((1+x)*(1-4*x+x^2)) )); // G. C. Greubel, Jan 09 2020
    
  • Maple
    seq(coeff(series((1-x+x^2)/((1+x)*(1-4*x+x^2)), x, n+1), x, n), n = 0..30); # G. C. Greubel, Jan 09 2020
  • Mathematica
    LinearRecurrence[{3,3,-1}, {1,2,10}, 30] (* G. C. Greubel, Jan 09 2020 *)
  • PARI
    my(x='x+O('x^30)); Vec((1-x+x^2)/((1+x)*(1-4*x+x^2))) \\ G. C. Greubel, Jan 09 2020
    
  • Sage
    def A146983_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1-x+x^2)/((1+x)*(1-4*x+x^2)) ).list()
    A146983_list(30) # G. C. Greubel, Jan 09 2020
    

Formula

From Peter Bala, May 01 2012: (Start)
a(n) = (-1)^n + 3*Sum_{k = 1..n} (-1)^(n-k)*6^(k-1)*binomial(n+k,2*k).
a(n) = (-1)^n*R(n,-3), where R(n,x) is the n-th row polynomial of A211955.
a(n) = (-1)^n*1/u*T(n,u)*T(n+1,u) with u = sqrt(-1/2) and T(n,x) denotes the Chebyshev polynomial of the first kind Cf. A182432.
Recurrence: a(n) = 4*a(n-1) -a(n-2) +3*(-1)^n, with a(0) = 1 and a(1) = 2; a(n)*a(n-2) = a(n-1)*(a(n-1)+3*(-1)^n).
Sum_{k>=0} (-1)^k/a(k) = 1/sqrt(3). (End)
From Colin Barker, Jul 29 2013: (Start)
a(n) = 3*a(n-1) + 3*a(n-2) - a(n-3).
G.f.: (1-x+x^2)/((1+x)*(1-4*x+x^2)). (End)

Extensions

More terms from Colin Barker, Jul 29 2013

A264357 Array A(r, n) of number of independent components of a symmetric traceless tensor of rank r and dimension n, written as triangle T(n, r) = A(r, n-r+2), n >= 1, r = 2..n+1.

Original entry on oeis.org

0, 2, 0, 5, 2, 0, 9, 7, 2, 0, 14, 16, 9, 2, 0, 20, 30, 25, 11, 2, 0, 27, 50, 55, 36, 13, 2, 0, 35, 77, 105, 91, 49, 15, 2, 0, 44, 112, 182, 196, 140, 64, 17, 2, 0, 54, 156, 294, 378, 336, 204, 81, 19, 2, 0
Offset: 1

Views

Author

Wolfdieter Lang, Dec 10 2015

Keywords

Comments

A (totally) symmetric traceless tensor of rank r >= 2 and dimension n >= 1 is irreducible.
The array of the number of independent components of a rank r symmetric traceless tensor A(r, n), for r >= 2 and n >=1, is given by risefac(n,r)/r! - risefac(n,r-2)/(r-2)!, where the first term gives the number of independent components of a symmetric tensors of rank r (see a Dec 10 2015 comment under A135278) and the second term is the number of constraints from the tracelessness requirement. The tensor has to be traceless in each pair of indices.
The first rows of the array A, or the first columns (without the first r-2 zeros) of the triangle T are for r = 2..6: A000096, A005581, A005582, A005583, A005584.
Equals A115241 with the first column of positive integers removed. - Georg Fischer, Jul 26 2023

Examples

			The array A(r, n) starts:
   r\n 1 2  3   4   5    6    7     8     9    10 ...
   2:  0 2  5   9  14   20   27    35    44    54
   3:  0 2  7  16  30   50   77   112   156   210
   4:  0 2  9  25  55  105  182   294   450   660
   5:  0 2 11  36  91  196  378   672  1122  1782
   6:  0 2 13  49 140  336  714  1386  2508  4290
   7:  0 2 15  64 204  540 1254  2640  5148  9438
   8:  0 2 17  81 285  825 2079  4719  9867 19305
   9:  0 2 19 100 385 1210 3289  8008 17875 37180
  10:  0 2 21 121 506 1716 5005 13013 30888 68068
  ...
The triangle T(n, r) starts:
   n\r  2   3   4   5   6   7  8  9 10 11 ...
   1:   0
   2:   2   0
   3:   5   2   0
   4:   9   7   2   0
   5:  14  16   9   2   0
   6:  20  30  25  11   2   0
   7:  27  50  55  36  13   2  0
   8:  35  77 105  91  49  15  2  0
   9:  44 112 182 196 140  64 17  2  0
  10:  54 156 294 378 336 204 81 19  2  0
  ...
A(r, 1) = 0 , r >= 2, because a symmetric rank r tensor t of dimension one has one component t(1,1,...,1) (r 1's) and if the traces vanish then t vanishes.
A(3, 2) = 2 because a symmetric rank 3 tensor t with three indices taking values from 1 or 2 (n=2) has the four independent components t(1,1,1), t(1,1,2), t(1,2,2), t(2,2,2), and (invoking symmetry) the vanishing traces are Sum_{j=1..2} t(j,j,1) = 0 and Sum_{j=1..2} t(j,j,2) = 0. These are two constraints, which can be used to eliminate, say, t(1,1,1) and t(2,2,2), leaving 2 = A(3, 2) independent components, say, t(1,1,2) and t(1,2,2).
From _Peter Luschny_, Dec 14 2015: (Start)
The diagonals diag(n, k) start:
   k\n  0       1       2       3       4      5       6
   0:   0,      2,      9,     36,    140,   540,   2079, ... A007946
   1:   2,      7,     25,     91,    336,  1254,   4719, ... A097613
   2:   5,     16,     55,    196,    714,  2640,   9867, ... A051960
   3:   9,     30,    105,    378,   1386,  5148,  19305, ... A029651
   4:  14,     50,    182,    672,   2508,  9438,  35750, ... A051924
   5:  20,     77,    294,   1122,   4290, 16445,  63206, ... A129869
   6:  27,    112,    450,   1782,   7007, 27456, 107406, ... A220101
   7:  35,    156,    660,   2717,  11011, 44200, 176358, ... A265612
   8:  44,    210,    935,    4004, 16744, 68952, 281010, ... A265613
  A000096,A005581,A005582,A005583,A005584.
(End)
		

Crossrefs

Programs

  • Mathematica
    A[r_, n_] := Pochhammer[n, r]/r! - Pochhammer[n, r-2]/(r-2)!;
    T[n_, r_] := A[r, n-r+2];
    Table[T[n, r], {n, 1, 10}, {r, 2, n+1}] (* Jean-François Alcover, Jun 28 2019 *)
  • Sage
    A = lambda r, n: rising_factorial(n,r)/factorial(r) - rising_factorial(n,r-2)/factorial(r-2)
    for r in (2..10): [A(r,n) for n in (1..10)] # Peter Luschny, Dec 13 2015

Formula

T(n, r) = A(r, n-r+2) with the array A(r, n) = risefac(n,r)/r! - risefac(n,r-2)/(r-2)! where the rising factorial risefac(n,k) = Product_{j=0..k-1} (n+j) and risefac(n,0) = 1.
From Peter Luschny, Dec 14 2015: (Start)
A(n+2, n+1) = A007946(n-1) = CatalanNumber(n)*3*n*(n+1)/(n+2) for n>=0.
A(n+2, n+2) = A024482(n+2) = A097613(n+2) = CatalanNumber(n+1)*(3*n+4)/2 for n>=0.
A(n+2, n+3) = A051960(n+1) = CatalanNumber(n+1)*(3*n+5) for n>=0.
A(n+2, n+4) = A029651(n+2) = CatalanNumber(n+1)*(6*n+9) for n>=0.
A(n+2, n+5) = A051924(n+3) = CatalanNumber(n+2)*(3*n+7) for n>=0.
A(n+2, n+6) = A129869(n+4) = CatalanNumber(n+2)*(3*n+8)*(2*n+5)/(n+4) for n>=0.
A(n+2, n+7) = A220101(n+4) = CatalanNumber(n+3)*(3*(n+3)^2)/(n+5) for n>=0.
A(n+2, n+8) = CatalanNumber(n+4)*(n+3)*(3*n+10)/(2*n+12) for n>=0.
Let for n>=0 and k>=0 diag(n,k) = A(k+2,n+k+1) and G(n,k) = 2^(k+2*n)*Gamma((3-(-1)^k+2*k+4*n)/4)/(sqrt(Pi)*Gamma(k+n+0^k)) then
diag(n,0) = G(n,0)*(n*3)/(n+2),
diag(n,1) = G(n,1)*(3*n+4)/((n+1)*(n+2)),
diag(n,2) = G(n,2)*(3*n+5)/(n+2),
diag(n,3) = G(n,3)*3,
diag(n,4) = G(n,4)*(3*n+7),
diag(n,5) = G(n,5)*(3*n+8),
diag(n,6) = G(n,6)*3*(3+n)^2,
diag(n,7) = G(n,7)*(3+n)*(10+3*n). (End)

A265613 a(n) = CatalanNumber(n+1)*n*(3*n^2+5*n+2)/((4+n)*(3+n)).

Original entry on oeis.org

0, 1, 8, 44, 210, 935, 4004, 16744, 68952, 281010, 1136960, 4576264, 18349630, 73370115, 292746300, 1166182800, 4639918800, 18443677230, 73261092240, 290845019400, 1154169552900, 4578702310182, 18159992594568, 72014135814704, 285542883894800, 1132125641947300
Offset: 0

Views

Author

Peter Luschny, Dec 15 2015

Keywords

Comments

This is row n=8 in the array A(n,k) = (rf(k+n-2,k-1)-(k-1)*(k-2)*rf(k+n-2, k-3))/ (k-1)! if n>=3 and A(n,0)=0, A(n,1)=1, A(n,2)=n; rf(n,k) denotes the rising factorial. See the cross-references for other values of n and the table in A264357.

Crossrefs

Programs

  • Maple
    A265613 := n -> (4*4^n*n*(n+1)*(3*n+2)*GAMMA(n+3/2))/(sqrt(Pi)*GAMMA(n+5)):
    seq(simplify(A265613(n)), n=0..25);
  • Mathematica
    Table[SeriesCoefficient[I (14 x^2 + I Sqrt[4 x - 1] (4 x^2 - 7 x + 2) - 11 x + 2 (1 - x^3))/(2 x^4 Sqrt[4 x - 1]), {x, 0, n}], {n, 0, 25}]
    (* or *)
    Table[(4^(n + 1) n (n + 1) (3 n + 2) Gamma[n + 3/2])/(Sqrt[Pi] Gamma[n + 5]), {n, 0, 25}] (* or *)
    Table[CatalanNumber(n+1) n (3 n^2 + 5 n + 2)/((4 + n) (3 + n)), {n, 0, 25}] (* Michael De Vlieger, Dec 15 2015 *)
  • Sage
    a = lambda n: catalan_number(n+1)*n*(3*n^2+5*n+2)/((4+n)*(3+n))
    [a(n) for n in range(26)]

Formula

G.f.: I*(14*x^2+I*sqrt(4*x-1)*(4*x^2-7*x+2)-11*x+2*(1-x^3))/(2*x^4*sqrt(4*x-1)).
a(n) = (4^(n+1)*n*(n+1)*(3*n+2)*Gamma(n+3/2))/(sqrt(Pi)*Gamma(n+5)).
a(n) = (rf(n+6, n-1)-(n-1)*(n-2)*rf(n+6, n-3))/(n-1)! for n>=3, rf(n,k) the rising factorial.
a(n) = a(n-1)*((2*(n+1))*(3*n+2)*(1+2*n)/((n-1)*(3*n-1)*(4+n))) for n>=2.
a(n) ~ 4^n*(12-(191/2)/n+(17595/32)/n^2-(705005/256)/n^3+(104705937/8192)/ n^4-...)/sqrt(n*Pi).
a(n) = [x^n] x*(1 + x)/(1 - x)^(n+5). - Ilya Gutkovskiy, Oct 09 2017

A028283 Central elements in 4-Pascal triangle A028275 (by row).

Original entry on oeis.org

1, 4, 10, 32, 110, 392, 1428, 5280, 19734, 74360, 281996, 1074944, 4115020, 15808912, 60917800, 235350720, 911315430, 3535767000, 13742347740, 53495534400, 208537056420, 813950932080, 3180614712600, 12441628655040
Offset: 0

Views

Author

Keywords

Comments

Equals A000984, [1, 2, 6, 20, 70, ...] convolved with [1, 2, 0, 0, 0, ...]. - Gary W. Adamson, Jun 05 2009

Crossrefs

Formula

a(n) = 2*A051960(n-1).
a(n) = 2*A000108(n)*(3n-1). - Ralf Stephan, Aug 24 2003

A274104 a(n) = Sum_{k=0..n} (3*k+2)*Catalan(k).

Original entry on oeis.org

2, 7, 23, 78, 274, 988, 3628, 13495, 50675, 191673, 729145, 2786655, 10691111, 41150011, 158825371, 614483086, 2382366586, 9253540456, 36001307656, 140269835866, 547245301906, 2137552658206, 8358366985726, 32715599554876, 128168506456852, 502538379368656, 1971926625140816
Offset: 0

Views

Author

N. J. A. Sloane, Jun 13 2016

Keywords

Crossrefs

Partial sums of A051960.

Programs

  • Magma
    [(&+[(3*k+2)*Catalan(k): k in [0..n]]): n in [0..40]]; // G. C. Greubel, Jun 30 2024
    
  • Mathematica
    CoefficientList[Series[(1 +2 x -Sqrt[1-4 x])/(2 x Sqrt[1-4 x] (1-x)), {x, 0, 50}], x] (* Vincenzo Librandi, Aug 18 2016 *)
  • SageMath
    [sum((3*k+2)*catalan_number(k) for k in range(n+1)) for n in range(41)] # G. C. Greubel, Jun 30 2024

Formula

D-finite with recurrence: (n+1)*a(n) - (3*n+5)*a(n-1) - 2*(3*n-8)*a(n-2) + 4*(2*n-3)*a(n-3) = 0. - R. J. Mathar, Jun 15 2016
G.f.: (1 + 2*x - sqrt(1-4*x))/(2*x*(1-x)*sqrt(1-4*x)). - Ilya Gutkovskiy, Jun 15 2016
a(n) = A014137(n+1) + (n+1)*A000108(n+1) - 1. - G. C. Greubel, Jun 30 2024
From Mélika Tebni, Sep 02 2024: (Start)
a(n) = A006134(n) + A006134(n+1)/2 - 1/2.
E.g.f.: exp(2*x)*(5*BesselI(0, 2*x)/2 + BesselI(1, 2*x)) + exp(x)/2*(3*Integral_{x=-oo..oo} BesselI(0,2*x)*exp(x) dx - 1). (End)

A383776 a(n) = (11*n + 3 + 6/(n+2)) * Catalan(n).

Original entry on oeis.org

6, 16, 53, 186, 672, 2472, 9207, 34606, 130988, 498576, 1906346, 7316596, 28170768, 108760560, 420889995, 1632155670, 6340808820, 24673450560, 96148670310, 375164728620, 1465589068320, 5731488987120, 22436098732710, 87905595401676, 344702077523352, 1352701532137312, 5312100899224532, 20874451526714856
Offset: 0

Views

Author

F. Chapoton, May 09 2025

Keywords

Comments

It appears that for n >= 2 a(n-2) is the number of lattice points in the n-dimensional lattice polytope defined, in the space with coordinates (x_1,x_2,...,x_n), by the equations x_i >= 0 for every i, sum_i x_i <= n and x_1 + x_2 <= 2. For n=2, this is a triangle with 6 lattice points.

Crossrefs

Programs

  • Mathematica
    A383776[n_] := (11*n + 3 + 6/(n + 2))*CatalanNumber[n];
    Array[A383776, 30, 0] (* Paolo Xausa, May 15 2025 *)
  • Sage
    [(11*n+3+6/(n+2))*catalan_number(n) for n in range(12)]

Formula

a(n) = (11*n + 3 + 6/(n + 2))*Catalan(n).
G.f.: 2*(7 + 5*sqrt(1 - 4*x) - 6*x)/((1 + sqrt(1 - 4*x))^2*sqrt(1 - 4*x)). - Stefano Spezia, May 15 2025

A241188 Triangle T(n,s) of Dynkin type D_n read by rows (n >= 2, 0 <= s <= n).

Original entry on oeis.org

1, 2, 1, 1, 3, 5, 5, 1, 4, 9, 16, 20, 1, 5, 14, 30, 55, 77, 1, 6, 20, 50, 105, 196, 294, 1, 7, 27, 77, 182, 378, 714, 1122, 1, 8, 35, 112, 294, 672, 1386, 2640, 4290, 1, 9, 44, 156, 450, 1122, 2508, 5148, 9867, 16445
Offset: 2

Views

Author

N. J. A. Sloane, Apr 24 2014

Keywords

Examples

			Triangle begins:
1, 2, 1,
1, 3, 5, 5,
1, 4, 9, 16, 20,
1, 5, 14, 30, 55, 77,
1, 6, 20, 50, 105, 196, 294,
1, 7, 27, 77, 182, 378, 714, 1122,
1, 8, 35, 112, 294, 672, 1386, 2640, 4290,
1, 9, 44, 156, 450, 1122, 2508, 5148, 9867, 16445,
...
		

Crossrefs

See A009766 for the case of type A.
See A059481 for the case of type B/C.
Diagonals give A029869, A051960, A029651, A051924. Row sums are also A051924.

Programs

  • Mathematica
    f[t_, s_] := Binomial[t, s] (s + t)/t;
    T[, 0] = 1; T[n, n_] := f[2 n - 2, n - 2]; T[n_, s_] := f[n + s - 2, s];
    Table[T[n, s], {n, 2, 9}, {s, 0, n}] // Flatten (* Jean-François Alcover, Feb 12 2019 *)

Formula

T(n,s) = [n+s-2,s] for 0 <= s < n, T(n,n) = [2n-2,n-2], where [t,s] stands for binomial(t,s)*(s+t)/t.

A367505 Triangle read by rows: row n gives the h-vector of the n-th halohedron.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 7, 7, 1, 1, 13, 27, 13, 1, 1, 21, 76, 76, 21, 1, 1, 31, 175, 300, 175, 31, 1, 1, 43, 351, 925, 925, 351, 43, 1, 1, 57, 637, 2401, 3675, 2401, 637, 57, 1, 1, 73, 1072, 5488, 11956, 11956, 5488, 1072, 73, 1, 1, 91, 1701, 11376, 33516, 47628, 33516, 11376, 1701, 91, 1
Offset: 0

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Author

F. Chapoton, Nov 21 2023

Keywords

Comments

Theorem 6.1.11 in Almeter's thesis gives the f-vector generating series. Then replacing x with x-1 gives the h-vector generating series.

Examples

			As a table:
  (1),
  (1,  1),
  (1,  3,  1),
  (1,  7,  7,  1),
  (1, 13, 27, 13,  1),
  (1, 21, 76, 76, 21,  1),
  ...
		

Crossrefs

Row sums are A051960(n-1) for n>=1.
Alternating sums form an aerated version of A110556.
Columns k=0-2 give A000012, A002061, A039623(n-1) for n>=2.

Programs

  • Mathematica
    T[0,0]:=1;T[n_,k_]:= Binomial[n-1,n-k]*Binomial[n,n-k]+Binomial[n-1,n-k-1]^2;Flatten[Table[T[n,k],{n,0,10},{k,0,n}]] (* Detlef Meya, Nov 23 2023 *)
  • Sage
    x = polygen(QQ, 'x')
    t = x.parent()[['t']].0
    F = (1 + (1+x) * t) / (2 * sqrt(1 - 2 * (x+1) * t + (x-1)**2 * t**2)) + 1/2
    for poly in F.list(): print(poly.list())

Formula

G.f.: (1 + (1+x)*t)/(2*sqrt(1 - 2*(x+1)*t + (x-1)^2*t^2)) + 1/2.
T(0,0) = 1; T(n,k) = binomial(n-1,n-k)*binomial(n,n-k)+binomial(n-1,n-k-1)^2. - Detlef Meya, Nov 23 2023
Showing 1-10 of 10 results.