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 13 results. Next

A278073 Triangle read by rows, coefficients of the polynomials P(m, n) = Sum_{k=1..n} binomial(m*n, m*k)* P(m, n-k)*z with P(m, 0) = 1 and m = 3.

Original entry on oeis.org

1, 0, 1, 0, 1, 20, 0, 1, 168, 1680, 0, 1, 1364, 55440, 369600, 0, 1, 10920, 1561560, 33633600, 168168000, 0, 1, 87380, 42771456, 2385102720, 34306272000, 137225088000, 0, 1, 699048, 1160164320, 158411809920, 5105916816000, 54752810112000, 182509367040000
Offset: 0

Views

Author

Peter Luschny, Jan 22 2017

Keywords

Examples

			Triangle begins:
[1]
[0, 1]
[0, 1,    20]
[0, 1,   168,    1680]
[0, 1,  1364,   55440,   369600]
[0, 1, 10920, 1561560, 33633600, 168168000]
		

Crossrefs

Cf. A014606 (diagonal), A243664 (row sums), A002115 (alternating row sums), A281479 (central coefficients), A327023 (refinement).
Cf. A097805 (m=0), A131689 (m=1), A241171 (m=2), A278074 (m=4).

Programs

  • Maple
    P := proc(m, n) option remember; if n = 0 then 1 else
    add(binomial(m*n, m*k)*P(m, n-k)*x, k=1..n) fi end:
    for n from 0 to 6 do PolynomialTools:-CoefficientList(P(3,n), x) od;
    # Alternatively:
    A278073_row := proc(n)
    1/(1-t*((1/3)*exp(x)+(2/3)*exp(-(1/2)*x)*cos((1/2)*x*sqrt(3))-1));
    expand(series(%,x,3*n+1)); (3*n)!*coeff(%,x,3*n);
    PolynomialTools:-CoefficientList(%,t) end:
    for n from 0 to 6 do A278073_row(n) od;
  • Mathematica
    With[{m = 3}, Table[Expand[j!*SeriesCoefficient[1/(1 - t*(MittagLefflerE[m, x^m] - 1)), {x, 0, j}]], {j, 0, 21, m}]];
    Function[arg, CoefficientList[arg, t]] /@ % // Flatten
  • Sage
    R = PowerSeriesRing(ZZ, 'x')
    x = R.gen().O(30)
    @cached_function
    def P(m, n):
        if n == 0: return R(1)
        return expand(sum(binomial(m*n, m*k)*P(m, n-k)*x for k in (1..n)))
    def A278073_row(n): return list(P(3, n))
    for n in (0..6): print(A278073_row(n)) # Peter Luschny, Mar 24 2020

Formula

E.g.f.: 1/(1-t*((1/3)*exp(x)+(2/3)*exp(-(1/2)*x)*cos((1/2)*x*sqrt(3))-1)), nonzero terms.

A178963 E.g.f.: (3+2*sqrt(3)*exp(x/2)*sin(sqrt(3)*x/2))/(exp(-x)+2*exp(x/2)*cos(sqrt(3)*x/2)).

Original entry on oeis.org

1, 1, 1, 1, 3, 9, 19, 99, 477, 1513, 11259, 74601, 315523, 3052323, 25740261, 136085041, 1620265923, 16591655817, 105261234643, 1488257158851, 17929265150637, 132705221399353, 2172534146099019, 30098784753112329, 254604707462013571, 4736552519729393091, 74180579084559895221, 705927677520644167681, 14708695606607601165843, 256937013876000351610089, 2716778010767155313771539
Offset: 0

Views

Author

N. J. A. Sloane, Dec 31 2010

Keywords

Comments

According to Mendes and Remmel, p. 56, this is the e.g.f. for 3-alternating permutations.

Crossrefs

Number of m-alternating permutations: A000012 (m=1), A000111 (m=2), A178963 (m=3), A178964 (m=4), A181936 (m=5).
Cf. A249402, A249583 (alternative definitions of 3-alternating permutations).

Programs

  • Maple
    A178963_list := proc(dim) local E,DIM,n,k;
    DIM := dim-1; E := array(0..DIM, 0..DIM); E[0,0] := 1;
    for n from 1 to DIM do
    if n mod 3 = 0 then E[n,0] := 0 ;
       for k from n-1 by -1 to 0 do E[k,n-k] := E[k+1,n-k-1] + E[k,n-k-1] od;
    else E[0,n] := 0;
       for k from 1 by 1 to n do E[k,n-k] := E[k-1,n-k+1] + E[k-1,n-k] od;
    fi od; [E[0,0],seq(E[k,0]+E[0,k],k=1..DIM)] end:
    A178963_list(30);  # Peter Luschny, Apr 02 2012
    # Alternatively, using a bivariate exponential generating function:
    A178963 := proc(n) local g, p, q;
    g := (x,z) -> 3*exp(x*z)/(exp(z)+2*exp(-z/2)*cos(z*sqrt(3)/2));
    p := (n,x) -> n!*coeff(series(g(x,z),z,n+2),z,n);
    q := (n,m) -> if modp(n,m) = 0 then 0 else 1 fi:
    (-1)^floor(n/3)*p(n,q(n,3)) end:
    seq(A178963(i),i=0..30); # Peter Luschny, Jun 06 2012
    # third Maple program:
    b:= proc(u, o, t) option remember; `if`(u+o=0, 1,
         `if`(t=0, add(b(u-j, o+j-1, irem(t+1, 3)), j=1..u),
                   add(b(u+j-1, o-j, irem(t+1, 3)), j=1..o)))
        end:
    a:= n-> b(n, 0, 0):
    seq(a(n), n=0..35);  # Alois P. Heinz, Oct 29 2014
  • Mathematica
    max = 30; f[x_] := (E^x*(2*Sqrt[3]*E^(x/2)*Sin[(Sqrt[3]*x)/2] + 3))/(2*E^((3*x)/2)*Cos[(Sqrt[3]*x)/2] + 1); CoefficientList[Series[f[x], {x, 0, max}], x]*Range[0, max]! // Simplify (* Jean-François Alcover, Sep 16 2013 *)
  • Sage
    # uses[A from A181936]
    A178963 = lambda n: (-1)^int(is_odd(n//3))*A(3,n)
    print([A178963(n) for n in (0..30)]) # Peter Luschny, Jan 24 2017

Formula

a(3*n) = A002115(n). - Peter Luschny, Aug 02 2012

A181985 Generalized Euler numbers. Square array A(n,k), n >= 1, k >= 0, read by antidiagonals. A(n,k) = n-alternating permutations of length n*k.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 19, 61, 1, 1, 1, 69, 1513, 1385, 1, 1, 1, 251, 33661, 315523, 50521, 1, 1, 1, 923, 750751, 60376809, 136085041, 2702765, 1, 1, 1, 3431, 17116009, 11593285251, 288294050521, 105261234643, 199360981, 1
Offset: 1

Views

Author

Peter Luschny, Apr 04 2012

Keywords

Comments

For an integer n > 0, a permutation s = s_1...s_k is an n-alternating permutation if it has the property that s_i < s_{i+1} if and only if n divides i.
The classical Euler numbers count 2-alternating permutations of length 2n.
Ludwig Seidel gave in 1877 an efficient algorithm to compute the coefficients of sec which carries immediately over to the computation of the generalized Euler numbers (see the Maple script).

Examples

			n\k [0][1]  [2]       [3]            [4]                 [5]
[1]  1, 1,   1,        1,             1,                   1
[2]  1, 1,   5,       61,          1385,               50521  [A000364]
[3]  1, 1,  19,     1513,        315523,           136085041  [A002115]
[4]  1, 1,  69,    33661,      60376809,        288294050521  [A211212]
[5]  1, 1, 251,   750751,   11593285251,     613498040952501
[6]  1, 1, 923, 17116009, 2301250545971, 1364944703949044401
       [A030662][A211213]   [A181991]
The (n,n)-diagonal is A181992.
		

Crossrefs

Programs

  • Maple
    A181985_list := proc(n, len) local E, dim, i, k;
    dim := n*(len-1); E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
       if i mod n = 0 then E[i, 0] := 0 ;
          for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
       else E[0, i] := 0;
          for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
       fi od;
    seq(E[0, n*k], k=0..len-1) end:
    for n from 1 to 6 do print(A181985_list(n, 6)) od;
  • Mathematica
    nmax = 9; A181985[n_, len_] := Module[{e, dim = n*(len - 1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0 , e[i, 0] = 0 ; For[k = i-1, k >= 0, k--, e[k, i-k] = e[k+1, i-k-1] + e[k, i-k-1] ], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i-k] = e[k-1, i-k+1] + e[k-1, i-k] ]; ]]; Table[e[0, n*k], { k, 0, len-1}]]; t = Table[A181985[n, nmax], {n, 1, nmax}]; a[n_, k_] := t[[n, k+1]]; Table[a[n-k, k], {n, 1, nmax}, {k, 0, n-1}] // Flatten (* Jean-François Alcover, Jun 27 2013, translated and adapted from Maple *)
  • Sage
    def A181985(m, n):
        shapes = ([x*m for x in p] for p in Partitions(n))
        return (-1)^n*sum((-1)^len(s)*factorial(len(s))*SetPartitions(sum(s), s).cardinality() for s in shapes)
    for m in (1..6): print([A181985(m, n) for n in (0..7)]) # Peter Luschny, Aug 10 2015

A211212 4-alternating permutations of length 4n.

Original entry on oeis.org

1, 1, 69, 33661, 60376809, 288294050521, 3019098162602349, 60921822444067346581, 2159058013333667522020689, 125339574046311949415000577841, 11289082167259099068433198467575829, 1510335441937894173173702826484473600301
Offset: 0

Views

Author

Peter Luschny, Apr 04 2012

Keywords

Comments

a(n) = A181985(4,n).

Crossrefs

Programs

  • Maple
    A211212 := proc(n) local E, dim, i, k; dim := 4*(n-1);
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
       if i mod 4 = 0 then E[i, 0] := 0 ;
          for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
       else E[0, i] := 0;
          for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
       fi od;
    E[0, dim] end:
    seq(A211212(i), i = 1..12);
    A211212_list := proc(size) local E, S;
    E := 2*exp(x*z)/(cosh(z)+cos(z));
    S := z -> series(E, z, 4*(size+1));
    seq((-1)^n*(4*n)!*subs(x=0, coeff(S(z), z, 4*n)), n=0..size-1) end:
    A211212_list(12); # Peter Luschny, Jun 06 2016
  • Mathematica
    A181985[n_, len_] := Module[{e, dim = n (len - 1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0, e[i, 0] = 0; For[k = i - 1, k >= 0, k--, e[k, i - k] = e[k + 1, i - k - 1] + e[k, i - k - 1]], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i - k] = e[k - 1, i - k + 1] + e[k - 1, i - k]]]]; Table[e[0, n k], {k, 0, len - 1}]];
    a[n_] := A181985[4, n + 1] // Last;
    Table[a[n], {n, 0, 11}] (* Jean-François Alcover, Jun 29 2019 *)
  • Sage
    # uses[A from A181936]
    A211212 = lambda n: A(4,4*n)*(-1)^n
    print([A211212(n) for n in (0..11)]) # Peter Luschny, Jan 24 2017

Formula

a(0) = 1; a(n) = Sum_{k=1..n} (-1)^(k+1) * binomial(4*n,4*k) * a(n-k). - Ilya Gutkovskiy, Jan 27 2020
E.g.f.: 1/(cos(x/sqrt(2))*cosh(x/sqrt(2))) = 1 + 1*z^4/4! + 69*z^8/8! + 33661*z^12/12! + ... - Michael Wallner, Nov 17 2020
a(n) ~ 2^(10*n + 9/2) * n^(4*n + 1/2) / (cosh(Pi/2) * Pi^(4*n + 1/2) * exp(4*n)). - Vaclav Kotesovec, Nov 17 2020

A215064 Triangle read by rows, e.g.f. exp(x*z)*((exp(x/2)+exp(x*3/2))/((exp(3*x/2)+ 2*cos(sqrt(3)*x/2))/3)-1).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, -1, 3, 3, 1, -3, -4, 6, 4, 1, -9, -15, -10, 10, 5, 1, 19, -54, -45, -20, 15, 6, 1, 99, 133, -189, -105, -35, 21, 7, 1, 477, 792, 532, -504, -210, -56, 28, 8, 1, -1513, 4293, 3564, 1596, -1134, -378, -84, 36, 9, 1, -11259
Offset: 0

Views

Author

Peter Luschny, Aug 01 2012

Keywords

Examples

			[0] [1]
[1] [1, 1]
[2] [1, 2, 1]
[3] [-1, 3, 3, 1]
[4] [-3, -4, 6, 4, 1]
[5] [-9, -15, -10, 10, 5, 1]
[6] [19, -54, -45, -20, 15, 6, 1]
[7] [99, 133, -189, -105, -35, 21, 7, 1]
[8] [477, 792, 532, -504, -210, -56, 28, 8, 1]
[9] [-1513, 4293, 3564, 1596, -1134, -378, -84, 36, 9, 1]
		

Crossrefs

Programs

  • Mathematica
    max = 11; f = Exp[x*z]*((Exp[x/2] + Exp[x*(3/2)])/((Exp[3*(x/2)] + 2*Cos[Sqrt[3]*(x/2)])/3) - 1); coes = CoefficientList[ Series[f, {x, 0, max}, {z, 0, max}], {x, z}]; Table[ coes[[n, k]]*(n - 1)!, {n, 1, max}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jul 29 2013 *)
  • Sage
    # uses[triangle from A215060]
    def A215064_triangle(dim):
        var('x, z')
        f = exp(x*z)*((exp(x/2)+exp(x*3/2))/((exp(3*x/2)+2*cos(sqrt(3)*x/2))/3)-1)
        return triangle(f, dim)
    A215064_triangle(12)

Formula

Matrix inverse is A215065.
T(n,k) = A215060(n,k) + A215062(n,k) - [n==k].
|T(n,0)| = A178963(n).
|T(3*n,0)| = A002115(n).

A215060 Triangle read by rows, e.g.f. exp(x*(z+1/2))/((exp(3*x/2) + 2*cos(sqrt(3)*x/2))/3).

Original entry on oeis.org

1, 0, 1, 0, 0, 1, -1, 0, 0, 1, 0, -4, 0, 0, 1, 0, 0, -10, 0, 0, 1, 19, 0, 0, -20, 0, 0, 1, 0, 133, 0, 0, -35, 0, 0, 1, 0, 0, 532, 0, 0, -56, 0, 0, 1, -1513, 0, 0, 1596, 0, 0, -84, 0, 0, 1, 0, -15130, 0, 0, 3990, 0, 0, -120, 0, 0, 1, 0, 0, -83215, 0
Offset: 0

Views

Author

Peter Luschny, Aug 01 2012

Keywords

Examples

			[0] [1]
[1] [0, 1]
[2] [0, 0, 1]
[3] [-1, 0, 0, 1]
[4] [0, -4, 0, 0, 1]
[5] [0, 0, -10, 0, 0, 1]
[6] [19, 0, 0, -20, 0, 0, 1]
[7] [0, 133, 0, 0, -35, 0, 0, 1]
[8] [0, 0, 532, 0, 0, -56, 0, 0, 1]
[9] [-1513, 0, 0, 1596, 0, 0, -84, 0, 0, 1]
		

Crossrefs

Programs

  • Sage
    def triangle(f, dim):
        var('x,z')
        s = f.series(x, dim+2)
        P = [factorial(i)*s.coefficient(x,i) for i in range(dim)]
        for k in range(dim): print([k], [P[k].coefficient(z,i) for i in (0..k)])
    def A215060_triangle(dim) :
        var('x, z')
        f = exp(x*(z+1/2))/((exp(3*x/2)+2*cos(sqrt(3)*x/2))/3)
        return triangle(f, dim)
    A215060_triangle(12)

Formula

Matrix inverse is A215061.
T(n,k) = A215064(n,k) - A215062(n,k) + [n==k].
|T(3*n,0)| = A002115(n).

A292604 Triangle read by rows, coefficients of generalized Eulerian polynomials F_{2}(x).

Original entry on oeis.org

1, 1, 0, 5, 1, 0, 61, 28, 1, 0, 1385, 1011, 123, 1, 0, 50521, 50666, 11706, 506, 1, 0, 2702765, 3448901, 1212146, 118546, 2041, 1, 0, 199360981, 308869464, 147485535, 24226000, 1130235, 8184, 1, 0
Offset: 0

Views

Author

Peter Luschny, Sep 20 2017

Keywords

Comments

The generalized Eulerian polynomials F_{m}(x) are defined F_{m; 0}(x) = 1 for all m >= 0 and for n > 0:
F_{0; n}(x) = Sum_{k=0..n} A097805(n, k)*(x-1)^(n-k) with coeffs. in A129186.
F_{1; n}(x) = Sum_{k=0..n} A131689(n, k)*(x-1)^(n-k) with coeffs. in A173018.
F_{2; n}(x) = Sum_{k=0..n} A241171(n, k)*(x-1)^(n-k) with coeffs. in A292604.
F_{3; n}(x) = Sum_{k=0..n} A278073(n, k)*(x-1)^(n-k) with coeffs. in A292605.
F_{4; n}(x) = Sum_{k=0..n} A278074(n, k)*(x-1)^(n-k) with coeffs. in A292606.
The case m = 1 are the Eulerian polynomials whose coefficients are the Eulerian numbers which are displayed in Euler's triangle A173018.
Evaluated at x in {-1, 1, 0} these families of polynomials give for the first few m:
F_{m} : F_{0} F_{1} F_{2} F_{3} F_{4}
x = 1: A000012 A000142 A000680 A014606 A014608 ... (m*n)!/m!^n
x = 0: -- A000012 A000364 A002115 A211212 ... m-alternating permutations of length m*n.
Note that the constant terms of the polynomials are the generalized Euler numbers as defined in A181985. In this sense generalized Euler numbers are also generalized Eulerian numbers.

Examples

			Triangle starts:
[n\k][    0        1        2       3     4  5  6]
--------------------------------------------------
[0][      1]
[1][      1,       0]
[2][      5,       1,       0]
[3][     61,      28,       1,      0]
[4][   1385,    1011,     123,      1,    0]
[5][  50521,   50666,   11706,    506,    1, 0]
[6][2702765, 3448901, 1212146, 118546, 2041, 1, 0]
		

References

  • G. Frobenius. Über die Bernoullischen Zahlen und die Eulerschen Polynome. Sitzungsber. Preuss. Akad. Wiss. Berlin, pages 200-208, 1910.

Crossrefs

F_{0} = A129186, F_{1} = A173018, F_{2} is this triangle, F_{3} = A292605, F_{4} = A292606.
First column: A000364. Row sums: A000680. Alternating row sums: A002105.

Programs

  • Maple
    Coeffs := f -> PolynomialTools:-CoefficientList(expand(f), x):
    A292604_row := proc(n) if n = 0 then return [1] fi;
    add(A241171(n, k)*(x-1)^(n-k), k=0..n); [op(Coeffs(%)), 0] end:
    for n from 0 to 6 do A292604_row(n) od;
  • Mathematica
    T[n_, k_] /; 1 <= k <= n := T[n, k] = k (2 k - 1) T[n - 1, k - 1] + k^2 T[n - 1, k]; T[, 1] = 1; T[, _] = 0;
    F[2, 0][] = 1; F[2, n][x_] := Sum[T[n, k] (x - 1)^(n - k), {k, 0, n}];
    row[n_] := If[n == 0, {1}, Append[CoefficientList[ F[2, n][x], x], 0]];
    Table[row[n], {n, 0, 7}] (* Jean-François Alcover, Jul 06 2019 *)
  • Sage
    def A292604_row(n):
        if n == 0: return [1]
        S = sum(A241171(n, k)*(x-1)^(n-k) for k in (0..n))
        return expand(S).list() + [0]
    for n in (0..6): print(A292604_row(n))

Formula

F_{2; n}(x) = Sum_{k=0..n} A241171(n, k)*(x-1)^(n-k) for n>0 and F_{2; 0}(x) = 1.

A292605 Triangle read by rows, coefficients of generalized Eulerian polynomials F_{3;n}(x).

Original entry on oeis.org

1, 1, 0, 19, 1, 0, 1513, 166, 1, 0, 315523, 52715, 1361, 1, 0, 136085041, 30543236, 1528806, 10916, 1, 0, 105261234643, 29664031413, 2257312622, 42421946, 87375, 1, 0, 132705221399353, 45011574747714, 4637635381695, 153778143100, 1156669095, 699042, 1, 0
Offset: 0

Views

Author

Peter Luschny, Sep 20 2017

Keywords

Comments

See the comments in A292604.

Examples

			Triangle starts:
[n\k][       0         1         2       3  4  5]
--------------------------------------------------
[0][         1]
[1][         1,        0]
[2][        19,        1,        0]
[3][      1513,      166,        1,     0]
[4][    315523,    52715,     1361,     1,  0]
[5][ 136085041, 30543236,  1528806, 10916,  1, 0]
		

Crossrefs

F_{0} = A129186, F_{1} = A173018, F_{2} = A292604, F_{3} is this triangle, F_{4} = A292606.
First column: A002115. Row sums: A014606. Alternating row sums: A292609.

Programs

  • Maple
    Coeffs := f -> PolynomialTools:-CoefficientList(expand(f),x):
    A292605_row := proc(n) if n = 0 then return [1] fi;
    add(A278073(n, k)*(x-1)^(n-k), k=0..n); [op(Coeffs(%)), 0] end:
    for n from 0 to 6 do A292605_row(n) od;
  • Sage
    # uses[A278073_row from A278073]
    def A292605_row(n):
        if n == 0: return [1]
        L = A278073_row(n)
        S = sum(L[k]*(x-1)^(n-k) for k in (0..n))
        return expand(S).list() + [0]
    for n in (0..5): print(A292605_row(n))

Formula

F_{3; n}(x) = Sum_{k=0..n} A278073(n, k)*(x-1)^(n-k) for n>0 and F_{3; 0}(x) = 1.

A326475 A(n, k) = (m*k)! [x^k] MittagLefflerE(m, x)^(-n), for m = 3, n >= 0, k >= 0; square array read by descending antidiagonals.

Original entry on oeis.org

1, 0, 1, 0, -1, 1, 0, 19, -2, 1, 0, -1513, 58, -3, 1, 0, 315523, -6218, 117, -4, 1, 0, -136085041, 1630330, -15795, 196, -5, 1, 0, 105261234643, -847053482, 4997781, -31924, 295, -6, 1, 0, -132705221399353, 766492673914, -3042574083, 11840836, -56285, 414, -7, 1
Offset: 0

Views

Author

Peter Luschny, Jul 08 2019

Keywords

Examples

			Array starts:
[0] 1,  0,   0,      0,        0,            0, ... A000007
[1] 1, -1,  19,  -1513,   315523,   -136085041, ... A002115
[2] 1, -2,  58,  -6218,  1630330,   -847053482, ...
[3] 1, -3, 117, -15795,  4997781,  -3042574083, ...
[4] 1, -4, 196, -31924, 11840836,  -8271354004, ...
[5] 1, -5, 295, -56285, 23952055, -18889306805, ...
[6] 1, -6, 414, -90558, 43493598, -38227720446, ...
		

Crossrefs

Cf. A326476 (m=2, p>=0), A326327 (m=2, p<=0), A326474 (m=3, p>=0), this sequence (m=3, p<=0).

Programs

  • Mathematica
    (* The function MLPower is defined in A326327. *)
    For[n = 0, n < 8, n++, Print[MLPower[3, -n, 8]]]
  • Sage
    # uses[MLPower from A326327]
    for n in (0..6): print(MLPower(3, -n, 9))

A327023 Ordered set partitions of the set {1, 2, ..., 3*n} with all block sizes divisible by 3, irregular triangle T(n, k) for n >= 0 and 0 <= k < A000041(n), read by rows.

Original entry on oeis.org

1, 1, 1, 20, 1, 168, 1680, 1, 440, 924, 55440, 369600, 1, 910, 10010, 300300, 1261260, 33633600, 168168000, 1, 1632, 37128, 48620, 1113840, 24504480, 17153136, 326726400, 2058376320, 34306272000, 137225088000
Offset: 0

Views

Author

Peter Luschny, Aug 27 2019

Keywords

Comments

T_{m}(n, k) gives the number of ordered set partitions of the set {1, 2, ..., m*n} into sized blocks of shape m*P(n, k), where P(n, k) is the k-th integer partition of n in the 'canonical' order A080577. Here we assume the rows of A080577 to be 0-based and m*[a, b, c,..., h] = [m*a, m*b, m*c,..., m*h]. Here is case m = 3. For instance 3*P(4, .) = [[12], [9, 3], [6, 6], [6, 3, 3], [3, 3, 3, 3]].

Examples

			Triangle starts (note the subdivisions by ';' (A072233)):
[0] [1]
[1] [1]
[2] [1;   20]
[3] [1;  168;  1680]
[4] [1;  440,   924;  55440;  369600]
[5] [1;  910, 10010; 300300, 1261260; 33633600; 168168000]
[6] [1; 1632, 37128,  48620; 1113840, 24504480,  17153136; 326726400, 2058376320;
     34306272000; 137225088000]
.
T(4, 1) = 440 because [9, 3] is the integer partition 3*P(4, 1) in the canonical order and there are 220 set partitions which have the shape [9, 3]. Finally, since the order of the sets is taken into account, one gets 2!*220 = 440.
		

Crossrefs

Row sums: A243664, alternating row sums: A002115, main diagonal: A014606, central column A281479, by length: A278073.
Cf. A178803 (m=0), A133314 (m=1), A327022 (m=2), this sequence (m=3), A327024 (m=4).

Programs

  • Sage
    # uses[GenOrdSetPart from A327022]
    def A327023row(n): return GenOrdSetPart(3, n)
    for n in (0..6): print(A327023row(n))
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