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.

A163844 Row sums of triangle A163841.

Original entry on oeis.org

1, 5, 25, 125, 621, 3065, 15051, 73645, 359485, 1752125, 8532591, 41537105, 202200415, 984526275, 4795673085, 23372376525, 113978687085, 556205251325, 2716129289775, 13273197773125, 64909884686595, 317652752793975, 1555587408645225, 7623031579626625
Offset: 0

Views

Author

Peter Luschny, Aug 06 2009

Keywords

Crossrefs

Programs

  • Maple
    swing := proc(n) option remember; if n = 0 then 1 elif
    irem(n, 2) = 1 then swing(n-1)*n else 4*swing(n-1)/n fi end:
    a := proc(n) local i,k; add(add(binomial(n-k,n-i)*swing(2*i),i=k..n),k=0..n) end:
  • Mathematica
    sf[n_] := n!/Quotient[n, 2]!^2; t[n_, k_] := Sum[Binomial[n - k, n - i]*sf[2*i], {i, k, n}]; Table[Sum[t[n, k], {k, 0, n}], {n, 0, 50}] (* G. C. Greubel, Aug 06 2017 *)

Formula

a(n) = Sum_{k=0..n} Sum_{i=k..n} binomial(n-k,n-i)*(2i)$ where i$ denotes the swinging factorial of i (A056040).

A163842 Triangle interpolating the swinging factorial (A056040) restricted to odd indices with its binomial transform. Same as interpolating the beta numbers 1/beta(n,n) (A002457) with (A163869). Triangle read by rows, for n >= 0, k >= 0.

Original entry on oeis.org

1, 7, 6, 43, 36, 30, 249, 206, 170, 140, 1395, 1146, 940, 770, 630, 7653, 6258, 5112, 4172, 3402, 2772, 41381, 33728, 27470, 22358, 18186, 14784, 12012, 221399, 180018, 146290, 118820, 96462, 78276, 63492, 51480
Offset: 0

Views

Author

Peter Luschny, Aug 06 2009

Keywords

Examples

			Triangle begins:
      1;
      7,     6;
     43,    36,    30;
    249,   206,   170,   140;
   1395,  1146,   940,   770,   630;
   7653,  6258,  5112,  4172,  3402,  2772;
  41381, 33728, 27470, 22358, 18186, 14784, 12012;
		

Crossrefs

Programs

  • Maple
    # Computes n rows of the triangle. For the functions 'SumTria' and 'swing' see A163840.
    a := n -> SumTria(k->swing(2*k+1),n,true);
  • Mathematica
    sf[n_] := n!/Quotient[n, 2]!^2; t[n_, k_] := Sum[Binomial[n-k, n-i]*sf[2*i+1], {i, k, n}]; Table[t[n, k], {n, 0, 7}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jun 28 2013 *)

Formula

T(n,k) = Sum_{i=k..n} binomial(n-k,n-i)*(2i+1)$ where i$ denotes the swinging factorial of i (A056040).

A163840 Triangle interpolating the binomial transform of the swinging factorial (A163865) with the swinging factorial (A056040).

Original entry on oeis.org

1, 2, 1, 5, 3, 2, 16, 11, 8, 6, 47, 31, 20, 12, 6, 146, 99, 68, 48, 36, 30, 447, 301, 202, 134, 86, 50, 20, 1380, 933, 632, 430, 296, 210, 160, 140, 4251, 2871, 1938, 1306, 876, 580, 370, 210, 70, 13102, 8851, 5980, 4042, 2736, 1860, 1280, 910, 700, 630
Offset: 0

Views

Author

Peter Luschny, Aug 06 2009

Keywords

Comments

Triangle read by rows.
An analog to the binomial triangle of the factorials (A076571).

Examples

			Triangle begins
    1;
    2,   1;
    5,   3,   2;
   16,  11,   8,   6;
   47,  31,  20,  12,  6;
  146,  99,  68,  48, 36, 30;
  447, 301, 202, 134, 86, 50, 20;
		

Crossrefs

Row sums are A163843.

Programs

  • Maple
    SumTria := proc(f,n,display) local m,A,j,i,T; T:=f(0);
    for m from 0 by 1 to n-1 do A[m] := f(m);
    for j from m by -1 to 1 do A[j-1] := A[j-1] + A[j] od;
    for i from 0 to m do T := T,A[i] od;
    if display then print(seq(T[i],i=nops([T])-m..nops([T]))) fi;
    od; subsop(1=NULL,[T]) end:
    swing := proc(n) option remember; if n = 0 then 1 elif
    irem(n, 2) = 1 then swing(n-1)*n else 4*swing(n-1)/n fi end:
    # Computes n rows of the triangle:
    A163840 := n -> SumTria(swing,n,true);
  • Mathematica
    sf[n_] := n!/Quotient[n, 2]!^2; t[n_, k_] := Sum[Binomial[n - k, n - i]*sf[i], {i, k, n}]; Table[t[n, k], {n, 0, 9}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jun 28 2013 *)

Formula

T(n,k) = Sum_{i=k..n} binomial(n-k,n-i)*i$ where i$ denotes the swinging factorial of i (A056040), for n >= 0, k >= 0.
Showing 1-3 of 3 results.