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.

A051714 Numerators of table a(n,k) read by antidiagonals: a(0,k) = 1/(k+1), a(n+1,k) = (k+1)*(a(n,k) - a(n,k+1)), n >= 0, k >= 0.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 3, 1, -1, 1, 1, 2, 1, -1, 0, 1, 1, 5, 2, -3, -1, 1, 1, 1, 3, 5, -1, -1, 1, 0, 1, 1, 7, 5, 0, -4, 1, 1, -1, 1, 1, 4, 7, 1, -1, -1, 1, -1, 0, 1, 1, 9, 28, 49, -29, -5, 8, 1, -5, 5, 1, 1, 5, 3, 8, -7, -9, 5, 7, -5, 5, 0, 1, 1, 11, 15, 27, -28, -343, 295, 200, -44, -1017, 691, -691
Offset: 0

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Author

Keywords

Comments

Leading column gives the Bernoulli numbers A164555/A027642. - corrected by Paul Curtz, Apr 17 2014

Examples

			Table begins:
   1     1/2   1/3    1/4   1/5  1/6  1/7 ...
   1/2   1/3   1/4    1/5   1/6  1/7 ...
   1/6   1/6   3/20   2/15  5/42 ...
   0     1/30  1/20   2/35  5/84 ...
  -1/30 -1/30 -3/140 -1/105 ...
Antidiagonals of numerator(a(n,k)):
  1;
  1,  1;
  1,  1,  1;
  1,  1,  1,  0;
  1,  1,  3,  1, -1;
  1,  1,  2,  1, -1,   0;
  1,  1,  5,  2, -3,  -1,  1;
  1,  1,  3,  5, -1,  -1,  1,  0;
  1,  1,  7,  5,  0,  -4,  1,  1, -1;
  1,  1,  4,  7,  1,  -1, -1,  1, -1,  0;
  1,  1,  9, 28, 49, -29, -5,  8,  1, -5,  5;
		

Crossrefs

Denominators are in A051715.

Programs

  • Magma
    function a(n,k)
      if n eq 0 then return 1/(k+1);
      else return (k+1)*(a(n-1,k) - a(n-1,k+1));
      end if;
    end function;
    A051714:= func< n,k | Numerator(a(n,k)) >;
    [A051714(k,n-k): k in [0..n], n in [0..15]]; // G. C. Greubel, Apr 22 2023
    
  • Maple
    a:= proc(n,k) option remember;
          `if`(n=0, 1/(k+1), (k+1)*(a(n-1,k)-a(n-1,k+1)))
        end:
    seq(seq(numer(a(n, d-n)), n=0..d), d=0..12); # Alois P. Heinz, Apr 17 2013
  • Mathematica
    nmax = 12; a[0, k_]:= 1/(k+1); a[n_, k_]:= a[n, k]= (k+1)(a[n-1, k]-a[n-1, k+1]); Numerator[Flatten[Table[a[n-k, k], {n,0,nmax}, {k, n, 0, -1}]]] (* Jean-François Alcover, Nov 28 2011 *)
  • SageMath
    def a(n,k):
        if (n==0): return 1/(k+1)
        else: return (k+1)*(a(n-1, k) - a(n-1, k+1))
    def A051714(n,k): return numerator(a(n, k))
    flatten([[A051714(k, n-k) for k in range(n+1)] for n in range(16)]) # G. C. Greubel, Apr 22 2023

Formula

From Fabián Pereyra, Jan 14 2023: (Start)
a(n,k) = numerator(Sum_{j=0..n} (-1)^(n-j)*j!*Stirling2(n,j)/(j+k+1)).
E.g.f.: A(x,t) = (x+log(1-t))/(1-t-exp(-x)) = (1+(1/2)*x+(1/6)*x^2/2!-(1/30)*x^4/4!+...)*1 + (1/2+(1/3)*x+(1/6)*x^2/2!+...)*t + (1/3+(1/4)*x+(3/20)*x^2/2!+...)*t^2 + .... (End)

Extensions

More terms from James Sellers, Dec 07 1999

A051715 Denominators of table a(n,k) read by antidiagonals: a(0,k) = 1/(k+1), a(n+1,k) = (k+1)(a(n,k)-a(n,k+1)), n >= 0, k >= 0.

Original entry on oeis.org

1, 2, 2, 3, 3, 6, 4, 4, 6, 1, 5, 5, 20, 30, 30, 6, 6, 15, 20, 30, 1, 7, 7, 42, 35, 140, 42, 42, 8, 8, 28, 84, 105, 28, 42, 1, 9, 9, 72, 84, 1, 105, 140, 30, 30, 10, 10, 45, 120, 140, 28, 105, 20, 30, 1, 11, 11, 110, 495, 3960, 924, 231, 165, 220, 66, 66, 12, 12, 66, 55, 495, 264, 308, 132, 165, 44, 66, 1
Offset: 0

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Author

Keywords

Comments

Leading column gives the Bernoulli numbers A027641/A027642.

Examples

			Table begins:
    1    1/2   1/3    1/4   1/5  1/6  1/7 ...
   1/2   1/3   1/4    1/5   1/6  1/7 ...
   1/6   1/6   3/20   2/15  5/42 ...
    0    1/30  1/20   2/35  5/84 ...
  -1/30 -1/30 -3/140 -1/105 ...
		

Crossrefs

Numerators are in A051714.

Programs

  • Maple
    a:= proc(n,k) option remember;
          `if`(n=0, 1/(k+1), (k+1)*(a(n-1,k)-a(n-1,k+1)))
        end:
    seq(seq(denom(a(n, d-n)), n=0..d), d=0..12); # Alois P. Heinz, Apr 17 2013
  • Mathematica
    nmax = 12; a[0, k_] := 1/(k+1); a[n_, k_] := a[n, k] = (k+1)(a[n-1, k]-a[n-1, k+1]); Denominator[ Flatten[ Table[ a[n-k, k], {n, 0, nmax}, {k, n, 0, -1}]]](* Jean-François Alcover, Nov 28 2011 *)

Formula

a(n,k) = denominator(Sum_{j=0..n} (-1)^(n-j)*j!*Stirling2(n,j)/(j+k+1)). - Fabián Pereyra, Jan 14 2023

Extensions

More terms from James Sellers, Dec 08 1999

A051723 Denominators of row 4 of table described in A051714/A051715.

Original entry on oeis.org

30, 30, 140, 105, 1, 140, 3960, 495, 1430, 6006, 5460, 130, 7140, 2040, 5168, 14535, 11970, 14630, 15180, 5313, 6325, 89700, 23400, 6825, 142506, 7830, 125860, 53940, 40920, 92752, 628320, 6545, 6290, 442890, 329004, 45695, 151905, 223860, 493640
Offset: 0

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Examples

			-1/30 -1/30 -3/140 -1/105 0 ...
		

Crossrefs

Cf. A051722.

Extensions

More terms from James Sellers, Dec 08 1999

A100652 Denominator of 1 - Sum_{i=1..n} |Bernoulli(i)|.

Original entry on oeis.org

1, 2, 3, 3, 10, 10, 105, 105, 70, 70, 1155, 1155, 1430, 1430, 2145, 2145, 24310, 24310, 4849845, 4849845, 58786, 58786, 2028117, 2028117, 965770, 965770, 1448655, 1448655, 28007330, 28007330, 100280245065, 100280245065, 66853496710, 66853496710, 100280245065
Offset: 1

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Author

N. J. A. Sloane, Dec 05 2004

Keywords

Comments

Contribution from Paul Curtz, Aug 07 2012 (Start):
Take a(0)=1. Then instead of the Akiyama-Tanigawa algorithm we create the extended (or prolonged) Akiyama-Tanigawa algorithm using A028310(n)=1,1,2,3,4,5,... instead of A000027(n)=1,2,3,4,5,.. .
Hence the array (A051714 with an additional column)
2, 1, 1/2, 1/3, 1/4,
1, 1/2, 1/3, 1/4, 1/5,
1/2, 1/6, 1/6, 3/20, 2/15, A026741(n+1)/A045896(n+1)
1/3, 0, 1/30, 1/20, 2/35, A194531(n)/A193220(n)
1/3, -1/30, -1/30, -3/140, -1/105. A051722(n)/A051723(n).
a(n) is the denominator of the (first) column before the Akiyama-Tanigawa algorithm leading to the second Bernoulli numbers A164555(n)/A027642(n). See A176672(n).
(End)

Examples

			1, 1/2, 1/3, 1/3, 3/10, 3/10, 29/105, 29/105, 17/70, 17/70, 193/1155, 193/1155, -123/1430, -123/1430, -2687/2145, -2687/2145, -202863/24310, -202863/24310, -307072861/4849845, ... = A100651/A100652.
		

Programs

  • Mathematica
    Denominator[1-(Accumulate[Abs[BernoulliB[Range[0,40]]]])] (* Harvey P. Dale, Jan 28 2013 *)
Showing 1-4 of 4 results.