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.

A277000 Numerators of an asymptotic series for the Gamma function (even power series).

Original entry on oeis.org

1, -1, 19, -2561, 874831, -319094777, 47095708213409, -751163826506551, 281559662236405100437, -49061598325832137241324057, 5012066724315488368700829665081, -26602063280041700132088988446735433, 40762630349420684160007591156102493590477
Offset: 0

Views

Author

Peter Luschny, Sep 25 2016

Keywords

Comments

Let y = x+1/2 then Gamma(x+1) ~ sqrt(2*Pi)*((y/E)*Sum_{k>=0} r(k)/y^(2*k))^y as x -> oo and r(k) = A277000(k)/A277001(k) (see example 6.1 in the Wang reference).

Examples

			The underlying rational sequence starts:
1, 0, -1/24, 0, 19/5760, 0, -2561/2903040, 0, 874831/1393459200, 0, ...
		

Crossrefs

Cf. A001163/A001164 (Stirling), A182935/A144618 (De Moivre), A005146/A005147 (Stieltjes), A090674/A090675 (Lanczos), A181855/A181856 (Nemes), A182912/A182913 (NemesG), A182916/A182917 (Wehmeier), A182919/A182920 (Gosper), A182914/A182915, A277002/A277003 (odd power series).
Cf. A276667/A276668 (the arguments of the Bell polynomials).

Programs

  • Maple
    b := n -> CompleteBellB(n, 0, seq((k-2)!*bernoulli(k,1/2), k=2..n))/n!:
    A277000 := n -> numer(b(2*n)): seq(A277000(n), n=0..12);
    # Alternatively the rational sequence by recurrence:
    R := proc(n) option remember; local k; `if`(n=0, 1,
    add(bernoulli(2*m+2,1/2)* R(n-m-1)/(2*m+1), m=0..n-1)/(2*n)) end:
    seq(numer(R(n)), n=0..12); # Peter Luschny, Sep 30 2016
  • Mathematica
    CompleteBellB[n_, zz_] := Sum[BellY[n, k, zz[[1 ;; n-k+1]]], {k, 1, n}];
    b[n_] := CompleteBellB[n, Join[{0}, Table[(k-2)! BernoulliB[k, 1/2], {k, 2, n}]]]/n!;
    a[n_] := Numerator[b[2n]];
    Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Sep 09 2018 *)

Formula

a(n) = numerator(b(2*n)) with b(n) = Y_{n}(0, z_2, z_3,..., z_n)/n! with z_k = k!*Bernoulli(k,1/2)/(k*(k-1)) and Y_{n} the complete Bell polynomials.
The rational numbers have the recurrence r(n) = (1/(2*n))*Sum_{m=0..n-1} Bernoulli(2*m+2,1/2)*r(n-m-1)/(2*m+1) for n>=1, r(0)=1. - Peter Luschny, Sep 30 2016

A181855 Numerator of Nemes numbers G_n.

Original entry on oeis.org

1, 1, 1, 239, -46409, 9113897, -695818219549, 5649766313929, -1070083202835456443, 93856597276403726428217, -4815785492460413153189484781, 674781102986061046417681986493, -9845646538265462155478818981872958283
Offset: 0

Views

Author

Peter Luschny, Dec 02 2010

Keywords

Comments

G(n) = A181855(n)/A181856(n). Nemes numbers provide the coefficients for an asymptotic expansion for the Gamma function for real arguments greater than or equal to one.
Gamma(x) = sqrt(2*Pi/x)*((x/e)*(Sum_{k=0..n-1} G_k x^(-2k) + R_n(x)))^x.

Examples

			G_0 = 1, G_1 = 1/12, G_2 = 1/1440, G_3 = 239/362880.
		

Crossrefs

Cf. A000367, A002445, A181856 (denominators).

Programs

  • Maple
    G := proc(n) option remember; local k; `if`(n=0,1,
    add(bernoulli(2*m+2)*G(n-m-1)/(2*m+1),m=0..n-1)/(2*n)) end;
    a181855 := n -> numer(G(n));
    # Alternatively:
    p := n -> CompleteBellB(n, 0, seq((k-2)!*bernoulli(k, 1), k=2..n))/n!:
    a := n -> numer(p(2*n)): seq(a(n), n=0..12); # Peter Luschny, Oct 03 2016
  • Mathematica
    a[0] = 1; a[n_] := a[n] = Sum[ BernoulliB[2m + 2]*a[n - m - 1]/(2m + 1), {m, 0, n}]/(2n); Table[a[n] // Numerator, {n, 0, 12}] (* Jean-François Alcover, Jul 26 2013 *)
    CompleteBellB[n_, zz_] := Sum[BellY[n, k, zz[[1 ;; n-k+1]]], {k, 1, n}];
    p[n_] := CompleteBellB[n, Join[{0}, Table[(k-2)! BernoulliB[k, 1], {k, 2, n}]]]/n!;
    a[n_] := Numerator[p[2n]];
    Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Sep 09 2018 *)

Formula

G_0 = 1 and for n > 1 and B_n denoting the Bernoulli number,
G_n = (1/(2*n)) * Sum_{m=0..n} B_{2*m+2} * G_{n-m-1} / (2*m+1).
a(n) = numerator(p(2*n)) with p(n) = Y_{n}(0, z_2, z_3, ..., z_n)/n! with z_k = (k-2)!*Bernoulli(k,1) and Y_{n} the complete Bell polynomials. - Peter Luschny, Oct 03 2016

A276996 Numerators of coefficients of polynomials arising from applying the complete Bell polynomials to k!B_k(x)/(k*(k-1)) with B_k(x) the Bernoulli polynomials.

Original entry on oeis.org

1, 0, 0, 1, -1, 1, 0, 1, -3, 1, 1, -1, 6, -10, 5, 0, -1, -15, 95, -40, 16, 239, -1, 13, -85, 240, -237, 79, 0, 403, 21, 385, -1575, 3577, -2947, 421, -46409, -239, 3841, 175, 861, -8036, 45458, -10692, 2673, 0, -82451, -2657, 56177, 1638, 19488, -85260, 139656, -86472, 19216
Offset: 0

Views

Author

Peter Luschny, Oct 01 2016

Keywords

Comments

The polynomials appear in certain asymptotic series for the Gamma function, cf. for example A181855/A181856 and A277000/A277001.

Examples

			Polynomials start:
p_0(x) = 1;
p_1(x) = 0;
p_2(x) = 1/6 + -x + x^2;
p_3(x) = (1/2)*x + -(3/2)*x^2 + x^3;
p_4(x) = 1/60 + -x + 6*x^2 + -10*x^3 + 5*x^4;
p_5(x) = -(1/6)*x + -(15/2)*x^2 + (95/3)*x^3 + -40*x^4 + 16*x^5;
p_6(x) = 239/504 + -(1/4)*x + (13/4)*x^2 + -85*x^3 + 240*x^4 + -237*x^5 + 79*x^6;
Triangle starts:
1;
0,   0;
1,  -1,   1;
0,   1,  -3,   1;
1,  -1,   6, -10,  5;
0,  -1, -15,  95, -40,   16;
239,-1,  13, -85, 240, -237, 79;
		

Crossrefs

Cf. A276997 (denominators); T(2n,0) = A181855(n), T(n,n) = A203852(n).
Cf. A276998.

Programs

  • Maple
    A276996_row := proc(n) local p;
    p := (n,x) -> CompleteBellB(n,0,seq((k-2)!*bernoulli(k,x),k=2..n)):
    seq(numer(coeff(p(n,x),x,k)), k=0..n) end:
    seq(A276996_row(n), n=0..9);
    # Recurrence for the polynomials:
    A276996_poly := proc(n,x) option remember; local z;
    if n = 0 then return 1 fi; z := proc(k) option remember;
    if k=1 then 0 else (k-2)!*bernoulli(k,x) fi end;
    expand(add(binomial(n-1,j)*z(n-j)*A276996_poly(j,x),j=0..n-1)) end:
    for n from 0 to 5 do sort(A276996_poly(n,x)) od;
  • Mathematica
    CompleteBellB[n_, zz_] := Sum[BellY[n, k, zz[[1 ;; n-k+1]]], {k, 1, n}];
    p[n_, x_] := CompleteBellB[n, Join[{0}, Table[(k-2)! BernoulliB[k, x], {k, 2, n}]]];
    row[0] = {1}; row[1] = {0, 0}; row[n_] := CoefficientList[p[n, x], x] // Numerator;
    Table[row[n], {n, 0, 9}] // Flatten (* Jean-François Alcover, Sep 09 2018 *)

Formula

T(n,k) = Numerator([x^k] p_n(x)) where p_n(x) = Y_{n}(z_1, z_2, z_3,..., z_n) are the complete Bell polynomials evaluated at z_1 = 0 and z_k = (k-2)!*B_k(x) for k>1 and B_k(x) the Bernoulli polynomials.
Showing 1-3 of 3 results.