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.

A054651 Triangle T(n,k) read by rows giving coefficients in expansion of n! * Sum_{i=0..n} C(x,i) in descending powers of x.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 0, 5, 6, 1, -2, 11, 14, 24, 1, -5, 25, 5, 94, 120, 1, -9, 55, -75, 304, 444, 720, 1, -14, 112, -350, 1099, 364, 3828, 5040, 1, -20, 210, -1064, 3969, -4340, 15980, 25584, 40320, 1, -27, 366, -2646, 12873, -31563, 79064, 34236, 270576, 362880
Offset: 0

Views

Author

N. J. A. Sloane, Apr 17 2000

Keywords

Comments

Apparently A190782 with reversed rows. - Mathew Englander, May 17 2014

Examples

			The first few polynomials are:
  1, 1+x, 2+x+x^2, 6+5*x+x^3, 24+14*x+11*x^2-2*x^3+x^4, ...
So the triangle begins:
  1;
  1,   1;
  1,   1,   2;
  1,   0,   5,     6;
  1,  -2,  11,    14,   24;
  1,  -5,  25,     5,   94,   120;
  1,  -9,  55,   -75,  304,   444,   720;
  1, -14, 112,  -350, 1099,   364,  3828,  5040;
  1, -20, 210, -1064, 3969, -4340, 15980, 25584, 40320;
  ...
		

Crossrefs

T(2*n,n) gives A347987.

Programs

  • Mathematica
    c[n_, k_] := Product[n-i, {i, 0, k-1}]/k!; row[n_] := CoefficientList[ n!*Sum[c[x, k], {k, 0, n}], x] // Reverse; Table[ row[n], {n, 0, 9}] // Flatten  (* Jean-François Alcover, Oct 04 2012 *)

Formula

T(n, k) = Sum_{i=0..k} Stirling1(i+n-k,n-k)*n!/(i+n-k)!. - Igor Victorovich Statsenko, May 27 2024

Extensions

Missing 0 corrected by Steve Marak - N. J. A. Sloane, Jul 27 2012

A054655 Triangle T(n,k) giving coefficients in expansion of n!*binomial(x-n,n) in powers of x.

Original entry on oeis.org

1, 1, -1, 1, -5, 6, 1, -12, 47, -60, 1, -22, 179, -638, 840, 1, -35, 485, -3325, 11274, -15120, 1, -51, 1075, -11985, 74524, -245004, 332640, 1, -70, 2086, -34300, 336049, -1961470, 6314664, -8648640, 1, -92, 3682, -83720, 1182769
Offset: 0

Views

Author

N. J. A. Sloane, Apr 18 2000

Keywords

Examples

			Triangle begins:
  1;
  1,  -1;
  1,  -5,    6;
  1, -12,   47,    -60;
  1, -22,  179,   -638,    840;
  1, -35,  485,  -3325,  11274,   -15120;
  1, -51, 1075, -11985,  74524,  -245004,  332640;
  1, -70, 2086, -34300, 336049, -1961470, 6314664, -8648640;
  ...
		

Crossrefs

Programs

  • Maple
    a054655_row := proc(n) local k; seq(coeff(expand((-1)^n*pochhammer (n-x,n)),x,n-k),k=0..n) end: # Peter Luschny, Nov 28 2010
  • Mathematica
    row[n_] := Table[ Coefficient[(-1)^n*Pochhammer[n - x, n], x, n - k], {k, 0, n}]; A054655 = Flatten[ Table[ row[n], {n, 0, 8}]] (* Jean-François Alcover, Apr 06 2012, after Maple *)
  • PARI
    T(n,k)=polcoef(n!*binomial(x-n,n), n-k);

Formula

n!*binomial(x-n, n) = Sum_{k=0..n} T(n, k)*x^(n-k).
From Robert Israel, Jul 12 2016: (Start)
G.f.: Sum_{n>=0} Sum_{k=0..n} T(n,k)*x^n*y^k = hypergeom([1, -1/(2*y), (1/2)*(-1+y)/y], [-1/y], -4*x*y).
E.g.f.: Sum_{n>=0} Sum_{k=0..n} T(n,k)*x^n*y^k/n! = (1+4*x*y)^(-1/2)*((1+sqrt(1+4*x*y))/2)^(1+1/y). (End)

A257635 Triangle with n-th row polynomial equal to Product_{k = 1..n} (x + n + k).

Original entry on oeis.org

1, 2, 1, 12, 7, 1, 120, 74, 15, 1, 1680, 1066, 251, 26, 1, 30240, 19524, 5000, 635, 40, 1, 665280, 434568, 117454, 16815, 1345, 57, 1, 17297280, 11393808, 3197348, 495544, 45815, 2527, 77, 1, 518918400, 343976400, 99236556, 16275700, 1659889, 107800, 4354, 100, 1
Offset: 0

Views

Author

Peter Bala, Nov 05 2015

Keywords

Comments

The row polynomials are a Sheffer sequence. For the associated polynomial sequence of binomial type see A038455.

Examples

			Triangle begins:
[0]       1;
[1]       2,      1;
[2]      12,      7,      1;
[3]     120,     74,     15,     1;
[4]    1680,   1066,    251,    26,    1;
[5]   30240,  19524,   5000,   635,   40,  1;
[6]  665280, 434568, 117454, 16815, 1345, 57, 1;
  ...
		

Crossrefs

Cf. A001813 (column 0), A005449 (first subdiagonal), A098118 (column 1).
Cf. A006963 (row sums), A000407 (alternating row sum).

Programs

  • Maple
    seq(seq(coeff(product(n + x + k, k = 1 .. n), x, i), i = 0..n), n = 0..8);
    # Alternative:
    p := n -> n!*hypergeom([-n, -x + n], [-n], 1):
    seq(seq((-1)^k*coeff(simplify(p(n)), x, k), k=0..n), n=0..6); # Peter Luschny, Nov 27 2021
  • Mathematica
    p[n_, x_] := FunctionExpand[Gamma[2*n + x + 1] / Gamma[n + x + 1]];
    Table[CoefficientList[p[n, x], x], {n,0,8}] // Flatten (* Peter Luschny, Mar 21 2022 *)

Formula

E.g.f.: A(x,t) = B(t)*C(t)^x = 1 + (2 + x)*t + (3 + x)*(4 + x)*t^2/2! + (4 + x)*(5 + x)*(6 + x)*t^3/3! + ..., where B(t) = 1/sqrt(1 - 4*t) is the o.g.f. for A000984 and C(t) = (1 - sqrt(1 - 4*t))/(2*t) is the o.g.f. for A000108.
n-th row polynomial: n!*binomial(2*n + x,n).
T(n, k) = (-1)^k*n!*[x^k] hypergeom([-n, -x + n], [-n], 1). - Peter Luschny, Nov 27 2021
T(n, k) = [x^k] Gamma(2*n + x + 1) / Gamma(n + x + 1). - Peter Luschny, Mar 21 2022

A347985 a(n) = [x^n] (2*n)! * Sum_{k=0..2*n} binomial(x-2*n,k).

Original entry on oeis.org

1, -3, 131, -8955, 893249, -117408375, 19180128407, -3747886705563, 852713408774513, -221431482383149467, 64629367172619230475, -20945446993569455512155, 7463226827397324296491489, -2899926767958744905966692575
Offset: 0

Views

Author

Seiichi Manyama, Sep 24 2021

Keywords

Crossrefs

Cf. A054649.

Programs

  • PARI
    a(n) = (2*n)!*polcoef(sum(k=n, 2*n, binomial(x-2*n, k)), n);

Formula

a(n) = A054649(2*n,n).
Showing 1-4 of 4 results.