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 1-5 of 5 results.

A369134 Triangle read by rows: T(n, k) = (-1)^(n + 1)*L(n) * M(n, k) where M is the inverse of the matrix generated by the triangle A368846 and L(n) is the lcm of the denominators of the terms in the n-th row of M.

Original entry on oeis.org

-1, 0, 1, 0, 0, -1, 0, 0, 7, 3, 0, 0, -14, -6, -1, 0, 0, 693, 297, 55, 5, 0, 0, -30030, -12870, -2431, -260, -15, 0, 0, 4150146, 1778634, 337480, 37310, 2625, 105, 0, 0, -21441420, -9189180, -1745458, -194480, -14280, -714, -21
Offset: 0

Views

Author

Peter Luschny, Jan 14 2024

Keywords

Comments

As has been observed by T. Curtright, the absolute value of the nonzero terms in row n of the triangle is monotonically decreasing, and the absolute value of each nonzero term T(n, k) is greater than the sum of the absolute value of the terms in the tail of that row.
The sum of the n-th row divided by the lcm of the n-th row of A368848 is the Bernoulli number B(2*n).

Examples

			[0] [-1]
[1] [0, 1]
[2] [0, 0,        -1]
[3] [0, 0,         7,        3]
[4] [0, 0,       -14,       -6,       -1]
[5] [0, 0,       693,      297,       55,       5]
[6] [0, 0,    -30030,   -12870,    -2431,    -260,    -15]
[7] [0, 0,   4150146,  1778634,   337480,   37310,   2625,  105]
[8] [0, 0, -21441420, -9189180, -1745458, -194480, -14280, -714, -21]
.
For n = 5:
(0 + 0 + 693 + 297 + 55 + 5) / 13860 = 5 / 66 = Bernoulli(10).
		

Crossrefs

Cf. A368846, A368848, A369135, A369120 (row sums), A369121 (T(n,n)), A369122 (T(n,2)), A000367/A002445 (Bernoulli(2n)).

Programs

  • Mathematica
    A368846[n_, k_] := If[k == 0, Boole[n == 0], (-1)^(n + k) 2 Binomial[2 k - 1, n] Binomial[2 n + 1, 2 k]];
    Map[# LCM @@ Denominator[#]&, MapIndexed[(-1)^First[#2] Take[#, First[#2]]&, Inverse[PadRight[Table[A368846[n, k], {n, 0, 10}, {k, 0, n}]]]]] (* Paolo Xausa, Jan 15 2024 *)
  • SageMath
    M = matrix(ZZ, 32, 32, A368846).inverse()
    def T(n, k):
        L = (-1)**(n + 1)*lcm(M[n][k].denominator() for k in range(n + 1))
        return L * M[n][k]
    for n in range(9):
        print([T(n, k) for k in range(n + 1)])

Formula

(Sum_{k=0..n} T(n, k)) / A369135(n) = Bernoulli(2*n).
T(n, 2) / T(n, 3) = 7 / 3 for n >= 3.

A369135 a(n) is the lcm of the denominators of the terms in the n-th row of M where M is the inverse of the matrix generated by the triangle A368846.

Original entry on oeis.org

1, 6, 30, 420, 630, 13860, 180180, 5405400, 4594590, 96996900, 1222160940, 40156716600, 6692786100, 281097016200, 1164544781400, 72201776446800, 2084826294901350, 1895296631728500, 222622144044300, 1823275359722817000, 575032998066426900, 129519337183533297000
Offset: 0

Views

Author

Peter Luschny, Jan 14 2024

Keywords

Comments

See A369134 for comments and formulas.

Crossrefs

Programs

  • Mathematica
    A368846[n_, k_] := If[k == 0, Boole[n == 0], (-1)^(n + k) 2 Binomial[2 k - 1, n] Binomial[2 n + 1, 2 k]];
    LCM @@@ Denominator[MapIndexed[Take[#, First[#2]]&, Inverse[PadRight[Table[ A368846[n, k], {n, 0, 25}, {k, 0, n}]]]]] (* Paolo Xausa, Jan 14 2024 *)
  • SageMath
    M = matrix(ZZ, 32, 32, A368846).inverse()
    def A369135(n): return lcm(M[n][k].denominator() for k in range(n + 1))
    print([A369135(n) for n in range(21)])

A368848 Triangle read by rows: T(n, k) = denominator(M(n, k)) where M is the inverse matrix of A368846.

Original entry on oeis.org

1, 1, 6, 1, 1, 30, 1, 1, 60, 140, 1, 1, 45, 105, 630, 1, 1, 20, 140, 252, 2772, 1, 1, 6, 14, 1260, 693, 12012, 1, 1, 900, 2100, 945, 5940, 10296, 51480, 1, 1, 3, 1, 945, 189, 1287, 6435, 218790, 1, 1, 100, 700, 420, 660, 12012, 780, 145860, 923780
Offset: 0

Views

Author

Peter Luschny, Jan 07 2024

Keywords

Comments

The row sums of the triangle, seen in its rational form A368847(n)/ A368848(n), are the unsigned Bernoulli numbers |B(2n)|. To get the signed Bernoulli numbers B(2n), one only needs to change the sign factor in the definition of A368846 from (-1)^(n + k) to (-1)^(n + 1).

Examples

			Triangle starts:
[0] [1]
[1] [1, 6]
[2] [1, 1,  30]
[3] [1, 1,  60,  140]
[4] [1, 1,  45,  105,  630]
[5] [1, 1,  20,  140,  252, 2772]
[6] [1, 1,   6,   14, 1260,  693, 12012]
[7] [1, 1, 900, 2100,  945, 5940,  10296, 51480]
[8] [1, 1,   3,    1,  945,  189,   1287,  6435, 218790]
		

Crossrefs

Cf. A368846 (inverse), A368847 (numerator), A002457 (main diagonal), A369134, A369135, A000367/A002445 (Bernoulli(2n)).

Programs

  • Mathematica
    A368846[n_,k_] := If[k==0, Boole[n==0], (-1)^(n+k) 2 Binomial[2k-1,n] Binomial[2n+1, 2k]];
    Denominator[MapIndexed[Take[#,First[#2]]&, Inverse[PadRight[Table[ A368846[n, k], {n,0,10},{k,0,n}]]]]] (* Paolo Xausa, Jan 08 2024 *)
  • SageMath
    M = matrix(ZZ, 10, 10, lambda n, k: A368846(n, k) if k <= n else 0)
    I = M.inverse()
    for n in range(9): print([I[n][k].denominator() for k in range(n+1)])

A368847 Triangle read by rows: T(n, k) = numerator(M(n, k)) where M is the inverse matrix of A368846.

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 3, 1, 1, 0, 0, 1, 1, 17, 1, 1, 0, 0, 691, 691, 59, 41, 5, 1, 0, 0, 14, 2, 359, 8, 4, 1, 1, 0, 0, 3617, 10851, 1237, 217, 293, 1, 7, 1, 0, 0, 43867, 43867, 750167, 6583, 943, 1129, 217, 2, 1, 0, 0, 1222277, 174611, 627073, 1540967, 28399, 53, 47, 23, 1, 1
Offset: 0

Views

Author

Peter Luschny, Jan 07 2024

Keywords

Comments

The row sums of the triangle, seen in its rational form A368847(n)/ A368848(n), are the unsigned Bernoulli numbers |B(2n)|. To get the signed Bernoulli numbers B(2n), one only needs to change the sign factor in the definition of A368846 from (-1)^(n + k) to (-1)^(n + 1).

Examples

			[0] [1]
[1] [0, 1]
[2] [0, 0,    1]
[3] [0, 0,    1,     1]
[4] [0, 0,    1,     1,    1]
[5] [0, 0,    1,     3,    1,   1]
[6] [0, 0,    1,     1,   17,   1,   1]
[7] [0, 0,  691,   691,   59,  41,   5, 1]
[8] [0, 0,   14,     2,  359,   8,   4, 1, 1]
[9] [0, 0, 3617, 10851, 1237, 217, 293, 1, 7, 1]
		

Crossrefs

Cf. A368846 (inverse), A368848 (denominator), A369134, A369135, A000367/A002445 (Bernoulli(2n)).

Programs

  • Mathematica
    A368846[n_,k_]:=If[k==0,Boole[n==0],(-1)^(n+k)2Binomial[2k-1,n]Binomial[2n+1,2k]];
    Numerator[MapIndexed[Take[#,First[#2]]&,Inverse[PadRight[Table[A368846[n,k],{n,0,10},{k,0,n}]]]]] (* Paolo Xausa, Jan 08 2024 *)
  • SageMath
    M = matrix(ZZ, 10, 10, lambda n, k: A368846(n, k) if k <= n else 0)
    I = M.inverse()
    for n in range(9): print([I[n][k].numerator() for k in range(n+1)])

A369120 a(n) = Sum_{k=0..n} A369134(n, k).

Original entry on oeis.org

-1, 1, -1, 10, -21, 1050, -45606, 6306300, -32585553, 5332033850, -646674981498, 248655336029100, -579463114572870, 400708622091878100, -31790012531476579380, 43435207772044760997000, -31514892593265599765292045, 814247185935070977732893250
Offset: 0

Views

Author

Peter Luschny, Jan 14 2024

Keywords

Comments

See A369134 for comments.

Crossrefs

Cf. A369134, A000367/A002445 (Bernoulli(2n)).

Programs

  • Mathematica
    A368846[n_, k_] := If[k == 0, Boole[n == 0], (-1)^(n + k) 2 Binomial[2 k - 1, n] Binomial[2 n + 1, 2 k]];
    Map[Total[# LCM @@ Denominator[#]]&, MapIndexed[(-1)^First[#2] Take[#, First[#2]]&, Inverse[PadRight[Table[A368846[n, k], {n, 0, 20}, {k, 0, n}]]]]] (* Paolo Xausa, Jan 16 2024 *)

Formula

a(n) / A369135(n) = Bernoulli(2*n).
Showing 1-5 of 5 results.