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.

A356547 Triangle read by rows. T(n, k) are the coefficients of polynomials p_n(x) based on the Eulerian numbers of second order representing the Bernoulli numbers as B_n = p_n(1) / (2*(2*n - 1)!).

Original entry on oeis.org

1, 1, 0, 6, -4, 0, 120, -192, 72, 0, 5040, -15840, 13920, -3456, 0, 362880, -2096640, 3306240, -1918080, 345600, 0, 39916800, -413683200, 1053803520, -1064448000, 448519680, -62208000, 0, 6227020800, -114960384000, 447866496000, -699342336000, 506348236800, -164428185600, 18289152000, 0
Offset: 0

Views

Author

Peter Luschny, Aug 12 2022

Keywords

Comments

The Bernoulli numbers with B(1) = 1/2 can be represented as the weighted sum of Eulerian numbers of second order, where we use the definition as given by Graham et al., Eulerian2(n, k) = A201637(n, k). For n >= 1 we have
B_(n) = (1/2)*Sum_{k=0..n} (-1)^k*Eulerian2(n, k) / binomial(2*n - 1, k).
Although this representation looks classical it was apparently first proved by Majer in 2010; later Fu and recently O'Sullivan gave an alternative proof (see links).
An analogous representation based on the Eulerian numbers of first order is given in A356545.

Examples

			The triangle T(n, k) of the coefficients, sorted in ascending order, starts:
[0]        1;
[1]        1,          0;
[2]        6,         -4,          0;
[3]      120,       -192,         72,           0;
[4]     5040,     -15840,      13920,       -3456,         0;
[5]   362880,   -2096640,    3306240,    -1918080,    345600,         0;
[6] 39916800, -413683200, 1053803520, -1064448000, 448519680, -62208000, 0;
		

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, 2nd ed. Addison-Wesley, Reading, MA, 1994, p. 270. (Since the thirty-fourth printing, Jan. 2022, with B(1) = 1/2.)

Crossrefs

Cf. A201637 (Eulerian number 2nd order), A164555(n)/A027642(n) (Bernoulli numbers with B(1) = 1/2).
Cf. A356545.

Programs

  • Maple
    E2 := proc(n, k) combinat:-eulerian2(n, k) end:
    p := (n, x) -> `if`(n = 0, 1, add(E2(n, k)*k!*(2*n - k - 1)!*(-x)^k, k = 0..n)):
    seq(print([n], seq(coeff(p(n, x), x, k), k = 0..n)), n = 0..7);
    seq(`if`(n = 0, 1, p(n, 1)/(2*(2*n-1)!)), n = 0..14); # check Bernoulli numbers

Formula

Let p_n(x) = Sum_{k=0..n} Eulerian2(n, k)*k!*(2*n - k - 1)! * (-x)^k.
T(n, k) = [x^k] p_n(x).
T(n, k) = (-1)^k*Eulerian2(n, k)*k!*(2*n - k - 1)!.

A356601 Triangle read by rows. T(n, k) = denominator(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, 2, 1, 6, 3, 1, 12, 3, 4, 1, 20, 30, 20, 5, 1, 30, 30, 10, 15, 6, 1, 42, 35, 70, 105, 14, 7, 1, 56, 7, 280, 35, 56, 7, 8, 1, 72, 252, 56, 630, 504, 28, 72, 9, 1, 90, 180, 105, 630, 126, 420, 45, 45, 10, 1, 110, 495, 33, 1155, 1386, 1155, 165, 99, 110, 11, 1
Offset: 0

Views

Author

Peter Luschny, Aug 15 2022

Keywords

Examples

			Triangle T(n, k) starts:
[0]  1;
[1]  2,   1;
[2]  6,   3,   1;
[3] 12,   3,   4,   1;
[4] 20,  30,  20,   5,   1;
[5] 30,  30,  10,  15,   6,   1;
[6] 42,  35,  70, 105,  14,   7,  1;
[7] 56,   7, 280,  35,  56,   7,  8,  1;
[8] 72, 252,  56, 630, 504,  28, 72,  9,  1;
[9] 90, 180, 105, 630, 126, 420, 45, 45, 10,  1;
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. A356602 (numerator), 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(denom(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[Denominator[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) = denominator(R(n, k)).

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.