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 1-3 of 3 results.

A356545 Triangle read by rows. T(n, k) are the coefficients of polynomials p_n(x) based on the Eulerian numbers of first order representing the Bernoulli numbers as B_n = p_n(1) / (n + 1)!.

Original entry on oeis.org

1, 1, 0, 2, -1, 0, 6, -8, 2, 0, 24, -66, 44, -6, 0, 120, -624, 792, -312, 24, 0, 720, -6840, 14496, -10872, 2736, -120, 0, 5040, -86400, 285840, -347904, 171504, -28800, 720, 0, 40320, -1244880, 6181920, -11245680, 8996544, -3090960, 355680, -5040, 0
Offset: 0

Views

Author

Peter Luschny, Aug 11 2022

Keywords

Comments

The Bernoulli numbers with B(1) = 1/2 can be represented as the weighted sum of Eulerian numbers, where we use the definition as given by Graham et al., Eulerian(n, k) = A173018(n, k). For n >= 0 we have
B_(n) = (1/(n + 1)) * Sum_{k=0..n} (-1)^k * Eulerian(n, k) / binomial(n, k).
The formula was given by Worpitsky in 1883 (see link) as an example for the application of a formula of Schlömilch from 1856. In 2019 the identity was proved in the modern fashion by Gessel on MathOverflow.
For a variant of this identity see the first formula in A356546.
An analogous representation based on the Eulerian numbers of second order is given in A356547.

Examples

			The table T(n, k) of the coefficients, sorted in ascending order, starts:
[0]     1;
[1]     1,        0;
[2]     2,       -1,       0;
[3]     6,       -8,       2,         0;
[4]    24,      -66,      44,        -6,       0;
[5]   120,     -624,     792,      -312,      24,        0;
[6]   720,    -6840,   14496,    -10872,    2736,     -120,      0;
[7]  5040,   -86400,  285840,   -347904,  171504,   -28800,    720,     0;
[8] 40320, -1244880, 6181920, -11245680, 8996544, -3090960, 355680, -5040, 0;
		

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, 2nd ed. Addison-Wesley, Reading, MA, 1994, p. 268. (Since the thirty-fourth printing, Jan. 2022, with B(1) = 1/2.)

Crossrefs

Cf. A173018 (Eulerian number), A164555(n)/A027642(n) (Bernoulli numbers with B(1) = 1/2), A129814 (row sums, but different sign for n = 1).

Programs

  • Maple
    E1 := proc(n, k) combinat:-eulerian1(n, k) end:
    p := (n, x) -> add(E1(n, k)*k!*(n - k)!*(-x)^k, k = 0..n):
    seq(print(seq(coeff(p(n, x), x, k), k=0..n)), n = 0..8);
    seq(p(n, 1)/(n + 1)!, n = 0..14); # check the Bernoulli representation
  • Mathematica
    T[n_, k_] := k! * (n-k)! * Sum[(-1)^(k-j) * (k-j+1)^n * Binomial[n+1, j], {j, 0, k}]; Table[T[n, k], {n, 0, 9}, {k, 0, n}] // TableForm
    (* Diagonals: *)
    d[n_, k_] := k! * (n - k)! * Sum[(-1)^(n-k-j)*(n - j - k + 1)^n * Binomial[n + 1, j], {j, 0, n - k}];

Formula

Let p_n(x) = Sum_{k=0..n} Eulerian(n, k)*k!*(n - k)! * (-x)^k. For x = 1 these polynomials give rise to the representation Bernoulli(n) = p_n(1) / (n + 1)!.
T(n, k) = [x^k] p_n(x).
T(n, k) = (-1)^k*Eulerian(n, k)*k!*(n - k)!.
T(n, k) = k! * (n-k)! * Sum_{j=0..k} (-1)^(k-j)*(k-j+1)^n*binomial(n+1, j).
T(n, k) = (-1)^k * A173018(n, k) * A098361(n, k).
T(n, k) = (-1)^k * A123125(n, n - k) * A098361(n, n - k).

A342321 T(n, k) = A343277(n)*[x^k] p(n, x) where p(n, x) = (1/(n+1))*Sum_{k=0..n} (-1)^k*E1(n, k)*x^(n - k) / binomial(n, k), and E1(n, k) are the Eulerian numbers A123125. Triangle read by rows, for 0 <= k <= n.

Original entry on oeis.org

1, 0, 1, 0, -1, 2, 0, 1, -4, 3, 0, -3, 22, -33, 12, 0, 1, -13, 33, -26, 5, 0, -5, 114, -453, 604, -285, 30, 0, 5, -200, 1191, -2416, 1985, -600, 35, 0, -35, 2470, -21465, 62476, -78095, 42930, -8645, 280, 0, 14, -1757, 21912, -88234, 156190, -132351, 51128, -7028, 126
Offset: 0

Views

Author

Peter Luschny, Mar 09 2021

Keywords

Comments

Conjecture: For even n >= 6 p(n, x)/x and for odd n >= 3 p(n, x)/(x^2 - x) is irreducible.

Examples

			Triangle starts:
[n]                T(n, k)                      A343277(n)
----------------------------------------------------------
[0] 1;                                                 [1]
[1] 0,  1;                                             [2]
[2] 0, -1,     2;                                      [6]
[3] 0,  1,    -4,     3;                              [12]
[4] 0, -3,    22,   -33,    12;                       [60]
[5] 0,  1,   -13,    33,   -26,     5;                [30]
[6] 0, -5,   114,  -453,   604,  -285,    30;        [210]
[7] 0,  5,  -200,  1191, -2416,  1985,  -600,  35;   [280]
.
The coefficients of the polynomials p(n, x) = (Sum_{k = 0..n} T(n, k) x^k) / A343277(n) for the first few n:
[0] 1;
[1] 0,   1/2;
[2] 0,  -1/6,    1/3;
[3] 0,  1/12,   -1/3,    1/4;
[4] 0, -1/20,   11/30, -11/20,    1/5;
[5] 0,  1/30,  -13/30,  11/10,  -13/15,  1/6.
		

Crossrefs

Sequences of rational polynomials p(n, x) with p(n, 1) = Bernoulli(n, 1):

Programs

  • Maple
    CoeffList := p -> op(PolynomialTools:-CoefficientList(p,x)):
    E1 := (n, k) -> combinat:-eulerian1(n, k):
    poly := n -> (1/(n+1))*add((-1)^k*E1(n,k)*x^(n-k)/binomial(n,k), k=0..n):
    Trow := n -> denom(poly(n))*CoeffList(poly(n)): seq(Trow(n), n = 0..9);
  • Mathematica
    Poly342321[n_, x_] := If[n == 0, 1, Sum[x^k*k!*Sum[(-1)^(n - j)*StirlingS2[n, j] /((k - j)!(n - j + 1) Binomial[n + 1, j]), {j, 0, k}], {k, 1, n}]];
    Table[A343277[n] CoefficientList[Poly342321[n, x], x][[k+1]], {n, 0, 9}, {k, 0, n}] // Flatten

Formula

An alternative representation of the sequence of rational polynomials is:
p(n, x) = Sum_{k=1..n} x^k*k!*Sum_{j=0..k} (-1)^(n-j)*Stirling2(n, j)/((k - j)!(n - j + 1)*binomial(n + 1, j)) for n >= 1 and p(0, x) = 1.
(Sum_{k = 0..n} T(n, k)) / A343277(n) = Bernoulli(n, 1).

A356602 Triangle read by rows. T(n, k) = numerator(Integral_{z=0..1} Eulerian(n, k)*z^(k + 1)*(z - 1)^(n - k - 1) dz), where Eulerian(n, k) = A173018(n, k) for n >= 1, and T(0, 0) = 1.

Original entry on oeis.org

1, 1, 0, -1, 1, 0, 1, -1, 1, 0, -1, 11, -11, 1, 0, 1, -13, 11, -13, 1, 0, -1, 19, -151, 302, -19, 1, 0, 1, -5, 1191, -302, 397, -15, 1, 0, -1, 247, -477, 15619, -15619, 477, -247, 1, 0, 1, -251, 1826, -44117, 15619, -44117, 1826, -251, 1, 0
Offset: 0

Views

Author

Peter Luschny, Aug 15 2022

Keywords

Examples

			Triangle T(n, k) starts:
[0]  1;
[1]  1,    0;
[2] -1,    1,    0;
[3]  1,   -1,    1,      0;
[4] -1,   11,  -11,      1,      0;
[5]  1,  -13,   11,    -13,      1,      0;
[6] -1,   19, -151,    302,    -19,      1,    0;
[7]  1,   -5, 1191,   -302,    397,    -15,    1,    0;
[8] -1,  247, -477,  15619, -15619,    477, -247,    1,  0;
[9]  1, -251, 1826, -44117,  15619, -44117, 1826, -251,  1,  0;
The Bernoulli numbers (with B(1) = 1/2) are the row sums of the fractions.
[0]   1                                              =     1;
[1] + 1/2                                            =   1/2;
[2] - 1/6  +  1/3                                    =   1/6;
[3] + 1/12 -  1/3  +    1/4                          =     0;
[4] - 1/20 + 11/30 -  11/20 +   1/5                  = -1/30;
[5] + 1/30 - 13/30 +  11/10 -  13/15  +   1/6        =     0;
[6] - 1/42 + 19/35 - 151/70 + 302/105 - 19/14 + 1/7  =  1/42;
		

Crossrefs

Cf. A356601 (denominator), A173018, A278075, A356545, A356547.

Programs

  • Maple
    E1 := proc(n, k) combinat:-eulerian1(n, k) end:
    Trow := proc(n, z) if n = 0 then return 1 fi;
    seq(numer(int(E1(n, k)*z^(k + 1)*(z - 1)^(n - k - 1), z=0..1)), k=0..n) end:
    for n from 0 to 9 do Trow(n, z) od;
  • Mathematica
    Unprotect[Power]; Power[0, 0] = 1;
    E1[n_, k_] /; n == k = 0^k; E1[n_, k_] /; k < 0 || k > n = 0;
    E1[n_, k_] := E1[n, k] = (k + 1)*E1[n - 1, k] + (n - k)*E1[n - 1, k - 1];
    T[n_, k_] /; n == k = 0^k;
    T[n_, k_] := (-1)^(k - n + 1)*E1[n, k]*Gamma[k + 2]*Gamma[n - k]/Gamma[n + 2];
    Table[Numerator[T[n, k]], {n, 0, 8}, {k, 0, n}] // TableForm

Formula

R(n, k) = (-1)^(k - n + 1)*Eulerian(n, k)*Gamma(k + 2)*Gamma(n - k)/Gamma(n + 2) for 0 <= k < n, and T(n, n) = 0^n.
Bernoulli(n) = Sum_{k=0..n} R(n, k), where Bernoulli(1) = 1/2.
T(n, k) = numerator(R(n, k)).
Showing 1-3 of 3 results.