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 1-10 of 18 results. Next

A051718 Numerators of column 2 of table described in A051714/A051715.

Original entry on oeis.org

1, 1, 3, 1, -3, -1, 1, 1, 1, -5, -1017, 691, 601, -7, -809, 3617, 922191, -43867, -6132631, 174611, 12988703, -854513, -1552922421, 236364091, 1139644561, -8553103, -7089687053, 23749461029, 378639019356093, -8615841276005
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 29; a[0, k_] := 1/(k + 1); a[n_, k_] := a[n, k] = (k + 1)*(a[n - 1, k] - a[n - 1, k + 1]); Table[a[n, k], {n, 0, nmax}, {k, 0, nmax}] [[All, 3]] // Numerator (* Jean-François Alcover, Oct 08 2012 *)

Formula

a(n) = numerator(n! * [x^n] f(x)) where f(x) = -(x*exp(3*x))/(1-exp(x))^3+5/(2*(1-exp(x)))-1/(1-exp(x))^2-5/6. - Vladimir Kruchinin, Nov 03 2015

Extensions

More terms from James Sellers, Dec 08 1999

A051720 Numerators of column 3 of table described in A051714/A051715.

Original entry on oeis.org

1, 1, 2, 2, -1, -4, -1, 8, 7, -44, -2663, 368, 1247, -244, -1511, 43416, 1623817, -276356, -10405289, -21376, 21491081, 32209348, -2523785339, -107638072, 1827648887, 842271812, -11254630547, -17380760743952, 596303510772251
Offset: 0

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Author

Keywords

Crossrefs

Cf. A051721.

Programs

  • Mathematica
    a[0, k_] := 1/(k+1); a[n_, k_] := a[n, k] = (k+1)*(a[n-1, k] - a[n-1, k+1]); a[n_] := a[n, 3] // Numerator; Table[a[n], {n, 0, 28}] (* Jean-François Alcover, Sep 17 2012 *)

Formula

a(n) = numerator(n! * [x^n] f(x)) where f(x) =(x*exp(4*x))/(1-exp(x))^4+13/(3*(1-exp(x)))-7/(2*(1-exp(x))^2)+1/(1-exp(x))^3-13/12. - Vladimir Kruchinin, Nov 03 2015

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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Author

Keywords

Examples

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

Crossrefs

Cf. A051722.

Extensions

More terms from James Sellers, Dec 08 1999

A051719 Denominators of column 2 of table described in A051714/A051715.

Original entry on oeis.org

3, 4, 20, 20, 140, 28, 140, 20, 220, 44, 20020, 1820, 1820, 4, 340, 340, 45220, 532, 29260, 220, 5060, 92, 41860, 1820, 1820, 4, 580, 580, 1384460, 9548, 811580, 340, 340, 4, 1279460, 1279460, 1279460, 4, 9020, 9020, 2715020, 1204, 138460, 460
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 43; a[0, k_] := 1/(k + 1); a[n_, k_] := a[n, k] = (k + 1)*(a[n - 1, k] - a[n - 1, k + 1]); Table[a[n, k], {n, 0, nmax}, {k, 0, nmax}] [[All, 3]] // Denominator (* Jean-François Alcover, Oct 08 2012 *)

Extensions

More terms from James Sellers, Dec 08 1999

A051721 Denominators of column 3 of table described in A051714/A051715.

Original entry on oeis.org

4, 5, 15, 35, 105, 105, 105, 165, 165, 455, 15015, 1365, 1365, 255, 255, 11305, 33915, 21945, 21945, 345, 3795, 10465, 31395, 1365, 1365, 435, 435, 346115, 1038345, 55335, 608685, 255, 255, 319865, 959595, 959595, 959595, 6765, 6765, 61705
Offset: 0

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Author

Keywords

Crossrefs

Cf. A051720.

Programs

  • Mathematica
    a[0, k_] := 1/(k+1); a[n_, k_] := a[n, k] = (k+1)*(a[n-1, k] - a[n-1, k+1]); a[n_] := a[n, 3] // Denominator; Table[a[n], {n, 0, 39}] (* Jean-François Alcover, Sep 17 2012 *)

Extensions

More terms from James Sellers, Dec 08 1999

A051722 Numerators of row 4 of table described in A051714/A051715.

Original entry on oeis.org

-1, -1, -3, -1, 0, 1, 49, 8, 27, 125, 121, 3, 169, 49, 125, 352, 289, 351, 361, 125, 147, 2057, 529, 152, 3125, 169, 2673, 1127, 841, 1875, 12493, 128, 121, 8381, 6125, 837, 2738, 3971, 8619, 1000, 1681, 1813, 35131, 1573, 3375, 21689, 2209, 4128, 26411
Offset: 0

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Author

Keywords

Examples

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

Crossrefs

Cf. A051723.

Extensions

More terms from James Sellers, Dec 08 1999

A051717 1, followed by denominators of first differences of Bernoulli numbers (B(i)-B(i-1)).

Original entry on oeis.org

1, 2, 3, 6, 30, 30, 42, 42, 30, 30, 66, 66, 2730, 2730, 6, 6, 510, 510, 798, 798, 330, 330, 138, 138, 2730, 2730, 6, 6, 870, 870, 14322, 14322, 510, 510, 6, 6, 1919190, 1919190, 6, 6, 13530, 13530, 1806, 1806, 690, 690, 282, 282, 46410, 46410, 66, 66, 1590, 1590
Offset: 0

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Keywords

Comments

Equivalently, denominators of Bernoulli twin numbers C(n) (cf. A051716).
The Bernoulli twin numbers C(n) are defined by C(0) = 1, then C(2n) = B(2n) + B(2n-1), C(2n+1) = -B(2n+1) - B(2n), where B() are the Bernoulli numbers A027641/A027642. The definition is due to Paul Curtz.
Denominators of column 1 of table described in A051714/A051715.

Examples

			Bernoulli numbers: 1, -1/2, 1/6, 0, -1/30, 0, 1/42, 0, -1/30, 0, 5/66, ...
First differences: -3/2, 2/3, -1/6, -1/30, 1/30, 1/42, -1/42, -1/30, ...
Numerators: -3, 2, -1, -1, 1, 1, -1, -1, 1, 5, -5, -691, 691, 7, ...
Denominators: 2, 3, 6, 30, 30, 42, 42, 30, 30, 66, 66, 2730, ...
Sequence of C(n)'s begins: 1, -1/2, -1/3, -1/6, -1/30, 1/30, 1/42, -1/42, -1/30, 1/30, 5/66, -5/66, -691/2730, 691/2730, 7/6, -7/6, ...
		

Crossrefs

Cf. A129724.
For numerators see A172083.

Programs

  • Magma
    f:= func< n | Bernoulli(n) + Bernoulli(n-1) >;
    function A051717(n)
      if n eq 0 then return 1;
      elif (n mod 2) eq 0 then return Denominator(f(n));
      else return Denominator(-f(n));
      end if;
    end function;
    [A051717(n): n in [0..50]]; // G. C. Greubel, Apr 22 2023
    
  • Maple
    C:=proc(n) if n=0 then RETURN(1); fi; if n mod 2 = 0 then RETURN(bernoulli(n)+bernoulli(n-1)); else RETURN(-bernoulli(n)-bernoulli(n-1)); fi; end;
  • Mathematica
    c[0]= 1; c[n_?EvenQ]:= BernoulliB[n] + BernoulliB[n-1]; c[n_?OddQ]:= -BernoulliB[n] - BernoulliB[n-1]; Table[Denominator[c[n]], {n,0,53}] (* Jean-François Alcover, Dec 19 2011 *)
    Join[{1},Denominator[Total/@Partition[BernoulliB[Range[0,60]],2,1]]] (* Harvey P. Dale, Mar 09 2013 *)
    Join[{1},Denominator[Differences[BernoulliB[Range[0,60]]]]] (* Harvey P. Dale, Jun 28 2021 *)
  • PARI
    a(n)=if(n<3,n+1,denominator(bernfrac(n)-bernfrac(n-1))) \\ Charles R Greathouse IV, May 18 2015
    
  • SageMath
    def f(n): return bernoulli(n)+bernoulli(n-1)
    def A051717(n):
        if (n==0): return 1
        elif (n%2==0): return denominator(f(n))
        else: return denominator(-f(n))
    [A051717(n) for n in range(51)] # G. C. Greubel, Apr 22 2023

Extensions

More terms from James Sellers, Dec 08 1999
Edited by N. J. A. Sloane, May 25 2008
Entry revised by N. J. A. Sloane, Apr 22 2021

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

A051716 Numerators of Bernoulli twin numbers C(n).

Original entry on oeis.org

1, -1, -1, -1, -1, 1, 1, -1, -1, 1, 5, -5, -691, 691, 7, -7, -3617, 3617, 43867, -43867, -174611, 174611, 854513, -854513, -236364091, 236364091, 8553103, -8553103, -23749461029, 23749461029, 8615841276005, -8615841276005, -7709321041217, 7709321041217, 2577687858367
Offset: 0

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Author

Keywords

Comments

The Bernoulli twin numbers C(n) are defined by C(0) = 1, then C(2n) = B(2n) + B(2n-1), C(2n+1) = -B(2n+1) - B(2n), where B() are the Bernoulli numbers A027641/A027642. The definition is due to Paul Curtz.
For denominators see A051717.
Negatives of numerators of column 1 of table described in A051714/A051715.

Examples

			The C(n) sequence is 1, -1/2, -1/3, -1/6, -1/30, 1/30, 1/42, -1/42, -1/30, 1/30, 5/66, -5/66, -691/2730, 691/2730, 7/6, -7/6, ...
		

Crossrefs

Programs

  • Magma
    f:= func< n | Bernoulli(n) + Bernoulli(n-1) >;
    function A051716(n)
      if n eq 0 then return 1;
      elif (n mod 2) eq 0 then return Numerator(f(n));
      else return Numerator(-f(n));
      end if;
    end function;
    [A051716(n): n in [0..50]]; // G. C. Greubel, Apr 22 2023
    
  • Maple
    C:=proc(n) if n=0 then RETURN(1); fi; if n mod 2 = 0 then RETURN(bernoulli(n)+bernoulli(n-1)); else RETURN(-bernoulli(n)-bernoulli(n-1)); fi; end;
  • Mathematica
    c[0]= 1; c[n_?EvenQ]:= BernoulliB[n] + BernoulliB[n-1]; c[n_?OddQ]:= -BernoulliB[n] - BernoulliB[n-1]; Table[Numerator[c[n]], {n,0,34}] (* Jean-François Alcover, Dec 19 2011 *)
  • PARI
    a(n) = if (n==0, 1, nu = numerator(bernfrac(n)+bernfrac(n-1)); if (n%2, -nu, nu)); \\ Michel Marcus, Jan 29 2017
    
  • SageMath
    def f(n): return bernoulli(n)+bernoulli(n-1)
    def A051716(n):
        if (n==0): return 1
        elif (n%2==0): return numerator(f(n))
        else: return numerator(-f(n))
    [A051716(n) for n in range(51)] # G. C. Greubel, Apr 22 2023

Formula

Numerators of differences of the sequence of rational numbers 0 followed by A164555/A027642. - Paul Curtz, Jan 29 2017
The e.g.f. of the rationals a(n)/A051717(n) is -(1/x + x^2/2 + x/(1 - exp(x)) + dilog(exp(-x))), (with dilog(x) = polylog(2, 1-x)). From integrating the e.g.f. of the z-sequence (exp(x) - (1+x))/(exp(x) -1)^2 for the Bernoulli polynomials of the second kind (A290317 / A290318). - Wolfdieter Lang, Aug 07 2017

Extensions

More terms from James Sellers, Dec 08 1999
Edited by N. J. A. Sloane, May 25 2008

A085738 Denominators in triangle formed from Bernoulli numbers.

Original entry on oeis.org

1, 2, 2, 6, 3, 6, 1, 6, 6, 1, 30, 30, 15, 30, 30, 1, 30, 15, 15, 30, 1, 42, 42, 105, 105, 105, 42, 42, 1, 42, 21, 105, 105, 21, 42, 1, 30, 30, 105, 105, 105, 105, 105, 30, 30, 1, 30, 15, 105, 105, 105, 105, 15, 30, 1, 66, 66, 165, 165, 1155, 231, 1155, 165, 165, 66, 66
Offset: 0

Views

Author

N. J. A. Sloane following a suggestion of J. H. Conway, Jul 23 2003

Keywords

Comments

Triangle is determined by rules 0) the top number is 1; 1) each number is the sum of the two below it; 2) it is left-right symmetric; 3) the numbers in each of the border rows, after the first 3, are alternately 0.
Up to signs this is the difference table of the Bernoulli numbers (see A212196). The Sage script below is based on L. Seidel's algorithm and does not make use of a library function for the Bernoulli numbers; in fact it generates the Bernoulli numbers on the fly. - Peter Luschny, May 04 2012

Examples

			Triangle begins
    1
   1/2,   1/2
   1/6,   1/3,   1/6
    0,    1/6,   1/6,     0
  -1/30,  1/30,  2/15,   1/30,  -1/30
    0,   -1/30,  1/15,   1/15,  -1/30,     0
   1/42, -1/42, -1/105,  8/105, -1/105,  -1/42,   1/42
    0,    1/42, -1/21,   4/105,  4/105,  -1/21,   1/42,   0
  -1/30,  1/30, -1/105, -4/105,  8/105,  -4/105, -1/105, 1/30, -1/30
		

Crossrefs

See A051714/A051715 for another triangle that generates the Bernoulli numbers.

Programs

  • Mathematica
    t[n_, 0] := (-1)^n BernoulliB[n];
    t[n_, k_] := t[n, k] = t[n-1, k-1] - t[n, k-1];
    Table[t[n, k] // Denominator, {n, 0, 10}, {k, 0, n}] (* Jean-François Alcover, Jun 04 2019 *)
  • Sage
    # uses[BernoulliDifferenceTable from A085737]
    def A085738_list(n): return [q.denominator() for q in BernoulliDifferenceTable(n)]
    A085738_list(6)
    # Peter Luschny, May 04 2012

Formula

T(n, 0) = (-1)^n*Bernoulli(n); T(n, k) = T(n-1, k-1) - T(n, k-1) for k=1..n. [Corrected (sign flipped) by R. J. Mathar, Jun 02 2010]
Let U(m, n) = (-1)^(m + n)*T(m+n, n). Then the e.g.f. for U(m, n) is (x - y)/(e^x - e^y). - Ira M. Gessel, Jun 12 2021
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