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 1-4 of 4 results.

A275213 The largest coefficients of the extended q-Catalan polynomials which are defined in A274886.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 5, 2, 12, 4, 32, 9, 94, 23, 289, 62, 910, 176, 2934, 512, 9686, 1551, 32540, 4822, 110780, 15266, 381676, 49141, 1328980, 160728, 4669367, 532890, 16535154, 1785162, 58965214, 6039328, 211591218, 20617808, 763535450, 70951548, 2769176514
Offset: 0

Views

Author

Peter Luschny, Jul 20 2016

Keywords

Crossrefs

Programs

  • Maple
    # Function QExtCatalan is defined in A274886.
    seq(max(QExtCatalan(n,q)), n=0..20);
  • Mathematica
    (* Function QExtCatalan is defined in A274886. *)
    Table[Max[CoefficientList[QExtCatalan[n] // FunctionExpand, q]], {n,0,30}]
  • Sage
    # uses[q_ext_catalan_number]
    # Function q_ext_catalan_number is in A274886.
    print([max(q_ext_catalan_number(n).list()) for n in (0..41)])

A274884 Triangle read by rows, coefficients of q-polynomials representing the oscillating orbitals over n sectors as A274888(n) - 2*A274886(n), a q-analog of A232500.

Original entry on oeis.org

-1, -1, -1, 1, -1, 0, 0, 1, -1, 1, 0, 1, 1, -1, 0, 0, 1, 2, 3, 2, 2, 1, -1, 1, 0, 1, 1, 3, 1, 2, 1, 1, -1, 0, 0, 1, 2, 5, 6, 9, 9, 10, 9, 8, 5, 4, 2, 1, -1, 1, 0, 1, 1, 3, 3, 5, 4, 5, 5, 5, 3, 3, 2, 1, 1
Offset: 0

Views

Author

Peter Luschny, Jul 20 2016

Keywords

Comments

The polynomials are univariate polynomials over the integers with degree floor((n+1)/2)^2 + ((n+1) mod 2). Evaluated at q=1 the polynomials give A232500.
For the combinatorial interpretation see A232500 and the link 'orbitals' (see also the illustrations there).

Examples

			The polynomials start:
[0] -1
[1] -1
[2] q - 1
[3] (q - 1) * (q^2 + q + 1)
[4] (q^2 + 1) * (q^2 + q - 1)
[5] (q^2 + 1) * (q^2 + q - 1) * (q^4 + q^3 + q^2 + q + 1)
[6] (q^2 - q + 1) * (q^3 + q^2 + q - 1) * (q^4 + q^3 + q^2 + q + 1)
The table starts:
[n] [k=0,1,2,...] [row sum]
[0] [-1] -1
[1] [-1] -1
[2] [-1, 1] 0
[3] [-1, 0, 0, 1] 0
[4] [-1, 1, 0, 1, 1] 2
[5] [-1, 0, 0, 1, 2, 3, 2, 2, 1] 10
[6] [-1, 1, 0, 1, 1, 3, 1, 2, 1, 1] 10
[7] [-1, 0, 0, 1, 2, 5, 6, 9, 9, 10, 9, 8, 5, 4, 2, 1] 70
[8] [-1, 1, 0, 1, 1, 3, 3, 5, 4, 5, 5, 5, 3, 3, 2, 1, 1] 42
		

Crossrefs

Cf. A232500 (row sums), A274886, A274888.

Programs

  • Maple
    QOscOrbitals := proc(n) local h, p, P, F, C, S;
    P := x -> QDifferenceEquations:-QPochhammer(q,q,x);
    F := x -> QDifferenceEquations:-QFactorial(x,q);
    h := iquo(n,2): p := `if`(n::even,1-q,1);
    C := (p*P(n))/(P(h)*P(h+1)); S := F(n)/F(h)^2;
    expand(simplify(expand(S-2*C))); seq(coeff(%,q,j), j=0..degree(%)) end:
    seq(QOscOrbitals(n), n=0..8);
  • Sage
    # uses[q_ext_catalan_number]
    # Function q_ext_catalan_number is in A274886.
    from sage.combinat.q_analogues import q_multinomial
    def q_osc_orbitals(n):
        return q_multinomial([n//2, n%2, n//2]) - 2*q_ext_catalan_number(n)
    for n in (0..9): print(q_osc_orbitals(n).list())

A274887 Triangle read by rows: coefficients of the q-factorial.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 1, 1, 3, 5, 6, 5, 3, 1, 1, 4, 9, 15, 20, 22, 20, 15, 9, 4, 1, 1, 5, 14, 29, 49, 71, 90, 101, 101, 90, 71, 49, 29, 14, 5, 1, 1, 6, 20, 49, 98, 169, 259, 359, 455, 531, 573, 573, 531, 455, 359, 259, 169, 98, 49, 20, 6, 1
Offset: 0

Views

Author

Peter Luschny, Jul 19 2016

Keywords

Comments

The main entry for this sequence is A008302 (Mahonian numbers).
q-factorial(n) is a univariate polynomial over the integers with degree n*(n-1)/2.
Evaluated at q=1 the q-factorial(n) gives the factorial A000142(n).

Examples

			The polynomials start:
[0] 1
[1] 1
[2] q + 1
[3] (q + 1) * (q^2 + q + 1)
[4] (q + 1)^2 * (q^2 + 1) * (q^2 + q + 1)
[5] (q + 1)^2 * (q^2 + 1) * (q^2 + q + 1) * (q^4 + q^3 + q^2 + q + 1)
The triangle starts:
[1]
[1]
[1, 1]
[1, 2, 2, 1]
[1, 3, 5, 6, 5, 3, 1]
[1, 4, 9, 15, 20, 22, 20, 15, 9, 4, 1]
[1, 5, 14, 29, 49, 71, 90, 101, 101, 90, 71, 49, 29, 14, 5, 1]
		

Crossrefs

Cf. A008302 (the same for all n > 0), A000142 (row sums), A063746 (q-central_binomial), A129175 (q-Catalan), A274886 (q-extended_Catalan), A274888 (q-swing_factorial), A275216 (q-binomial), A275215 (q-Narayana).

Programs

  • Magma
    B:= func< n,x | n eq 0 select 1 else (&*[1-x^j: j in [1..n]])/(1-x)^n >;
    R:=PowerSeriesRing(Integers(), 30);
    [Coefficients(R!( B(n,x) )): n in [0..9]]; // G. C. Greubel, May 22 2019
    
  • Mathematica
    Table[CoefficientList[QFactorial[n,q]//FunctionExpand, q], {n,0,9} ]//Flatten
  • PARI
    for(n=0, 8, print1(Vec(if(n==0, 1, prod(j=1, n, 1-x^j)/(1-x)^n)), ", "); print(); ) \\ G. C. Greubel, May 23 2019
  • Sage
    from sage.combinat.q_analogues import q_factorial
    for n in (0..5): print(q_factorial(n).list())
    

Formula

a(n) = A008302(n) for all n > 0. - M. F. Hasler, Jan 06 2024

A274885 Coefficients of some q-polynomials, P_n(q) = q_factorial(n+1) / (q_factorial([n/2]) * q_factorial([(n+2)/2])) with [.] the floor function.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 2, 1, 1, 1, 2, 2, 2, 1, 1, 1, 2, 4, 6, 8, 9, 9, 8, 6, 4, 2, 1, 1, 1, 2, 3, 4, 4, 5, 4, 4, 3, 2, 1, 1, 1, 2, 4, 7, 11, 15, 20, 24, 27, 29, 29, 27, 24, 20, 15, 11, 7, 4, 2, 1, 1, 1, 2, 3, 5, 6, 8, 9, 11, 11, 12, 11, 11, 9, 8, 6, 5, 3, 2, 1, 1
Offset: 0

Views

Author

Peter Luschny, Jul 20 2016

Keywords

Examples

			The polynomials start:
[0] 1
[1] q + 1
[2] q^2 + q + 1
[3] (q + 1) * (q^2 + 1) * (q^2 + q + 1)
[4] (q^2 + 1) * (q^4 + q^3 + q^2 + q + 1)
[5] (q + 1)*(q^2 - q + 1)*(q^2 + 1)*(q^2 + q + 1) * (q^4 + q^3 + q^2 + q + 1)
Triangle starts:
[0] [1]
[1] [1, 1]
[2] [1, 1, 1]
[3] [1, 2, 3, 3, 2, 1]
[4] [1, 1, 2, 2, 2, 1, 1]
[5] [1, 2, 4, 6, 8, 9, 9, 8, 6, 4, 2, 1]
[6] [1, 1, 2, 3, 4, 4, 5, 4, 4, 3, 2, 1, 1]
[7] [1, 2, 4, 7, 11, 15, 20, 24, 27, 29, 29, 27, 24, 20, 15, 11, 7, 4, 2, 1]
		

Crossrefs

Cf. Row sums are A212303(n+1) and A275212(n,0), A274886.

Programs

  • Magma
    QFac:= func< n, x | n eq 0 select 1 else (&*[1-x^j: j in [1..n]])/(1-x)^n >;
    P:= func< n,x | QFac(n+1,x)/( QFac(Floor(n/2),x)*QFac(Floor((n+2)/2),x) ) >;
    R:=PowerSeriesRing(Integers(), 30);
    [Coefficients(R!( P(n,x) )): n in [0..8]]; // G. C. Greubel, May 22 2019
  • Maple
    Qbinom1 := proc(n) local F, h; h := iquo(n,2);
    F := x -> QDifferenceEquations:-QFactorial(x,q);
    F(n+1)/(F(h)*F(h+1)); expand(simplify(expand(%)));
    seq(coeff(%,q,j), j=0..degree(%)) end: seq(Qbinom1(n), n=0..8);
  • Mathematica
    QBinom1[n_] := QFactorial[n+1,q] / (QFactorial[Quotient[n,2],q] QFactorial[Quotient[n+2,2],q]); Table[CoefficientList[QBinom1[n] // FunctionExpand,q], {n,0,8}] // Flatten
  • Sage
    from sage.combinat.q_analogues import q_factorial
    def q_binom1(n): return (q_factorial(n+1)//(q_factorial(n//2)* q_factorial((n+2)//2)))
    for n in (0..10): print(q_binom1(n).list())
    
Showing 1-4 of 4 results.