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.

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A321958 Sums of antidiagonals of A321960.

Original entry on oeis.org

1, 1, 2, 5, 15, 54, 227, 1085, 5774, 33679, 212807, 1443622, 10439565, 80016693, 646976322, 5496339141, 48894262619, 454113866430, 4392175247939, 44138842357617, 459956754593094, 4961220069886511, 55301147935270395, 636091223462294518, 7539926971001192381
Offset: 0

Views

Author

Peter Luschny, Dec 27 2018

Keywords

Crossrefs

Cf. A321960.

Programs

  • Sage
    def A321958List(l):
        def row(n, dim):
            m = 1
            for k in range(dim-1, -1, -1):
                ax = (n+k)*x
                m = 1 - ax - (ax*x)/m
            return SR(1/m).series(x, dim).list()
        return [sum(row(n-k, n+1)[k] for k in (0..n)) for n in (0..l-1)]
    A321958List(16)

A321964 Array of sequences read by descending antidiagonals, row A(n) is Stieltjes generated from the sequence n, n+1, n+2, n+3, ....

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 3, 2, 1, 0, 15, 10, 3, 1, 0, 105, 74, 21, 4, 1, 0, 945, 706, 207, 36, 5, 1, 0, 10395, 8162, 2529, 444, 55, 6, 1, 0, 135135, 110410, 36243, 6636, 815, 78, 7, 1, 0, 2027025, 1708394, 591381, 114084, 14425, 1350, 105, 8, 1
Offset: 0

Views

Author

Peter Luschny, Dec 26 2018

Keywords

Examples

			First few rows of the array start:
[0] 1, 0,  0,    0,     0,      0,        0,         0, ... A000007
[1] 1, 1,  3,   15,   105,    945,    10395,    135135, ... A001147
[2] 1, 2, 10,   74,   706,   8162,   110410,   1708394, ... A000698
[3] 1, 3, 21,  207,  2529,  36243,   591381,  10786527, ... A167872
[4] 1, 4, 36,  444,  6636, 114084,  2194596,  46460124, ... A321963
[5] 1, 5, 55,  815, 14425, 289925,  6444175, 155928575, ...
[6] 1, 6, 78, 1350, 27630, 636390, 16074990, 438572070, ...
Seen as triangle:
[0] 1;
[1] 0,      1;
[2] 0,      1,      1;
[3] 0,      3,      2,     1;
[4] 0,     15,     10,     3,    1;
[5] 0,    105,     74,    21,    4,   1;
[6] 0,    945,    706,   207,   36,   5,  1;
[7] 0,  10395,   8162,  2529,  444,  55,  6, 1;
[8] 0, 135135, 110410, 36243, 6636, 815, 78, 7, 1;
		

Crossrefs

Rows of array: A000007, A001147, A000698, A167872, A321963.
Columns include: A014105. Row sums of triangle: A321961.
Cf. A321960.

Programs

  • Maple
    JacobiCF := proc(a, b, p:=2) local m, k;
        m := 1;
        for k from nops(a) by -1 to 1 do
            m := 1 - b[k]*x - a[k]*x^p/m od;
        return 1/m end:
    JacobiGF := proc(a, b, p:=2) local cf, l, ser;
        cf := JacobiCF(a, b, p);
        l := min(nops(a), nops(b));
        ser := series(cf, x, l);
        seq(coeff(ser, x, n), n = 0..l-1) end:
    JacobiSquare := proc(a, p:=2) local cf, ser;
        cf := JacobiCF(a, a, p);
        ser := series(cf, x, nops(a));
        seq(coeff(ser, x, n), n = 0..nops(a)-1) end:
    StieltjesGF := proc(a, p:=2) local z, cf, ser;
        z := [seq(0, n = 1..nops(a))];
        cf := JacobiCF(a, z, p);
        ser := series(cf, x, nops(a));
        seq(coeff(ser, x, n), n = 0..nops(a)-1) end:
    s := n -> [seq(n+k, k = 0..9)]:
    Trow := n -> StieltjesGF(s(n), 1):
    for n from 0 to 6 do lprint(Trow(n)) od;
  • Mathematica
    nmax = 9;
    JacobiCF[a_, b_, p_:2] := Module[{m, k},  m = 1; For[k = Length[a] , k >= 1, k--, m = 1 - b[[k]]*x - a[[k]]*x^p/m ]; 1/m];
    JacobiGF[a_, b_, p_:2] := Module[{cf, l, ser}, cf = JacobiCF[a, b, p]; l = Min[Length[a], Length[b]]; ser = Series[cf, {x, 0, l}]; CoefficientList[ ser, x]];
    JacobiSquare[a_, p_:2] := Module[{cf, ser}, cf = JacobiCF[a, a, p]; ser = Series[cf, {x, 0, Length[a]}]; CoefficientList[ser, x]];
    StieltjesGF[a_, p_:2] := Module[{z, cf, ser}, z = Table[0, Length[a]]; cf = JacobiCF[a, z, p]; ser = Series[cf, {x, 0, Length[a]}]; CoefficientList[ ser, x]];
    s[n_] := Table[n + k, {k, 0, nmax}];
    Trow[0] = Table[Boole[k == 0], {k, 0, nmax}];
    Trow[n_] := Trow[n] = StieltjesGF[s[n], 1] ;
    T[n_, k_] := Trow[n][[k + 1]];
    Table[T[n - k, k], {n, 0, nmax}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Jan 07 2019, translated from Maple *)
  • Sage
    # uses[StieltjesGF from A321960]
    def Trow(n, dim): return StieltjesGF(lambda k: n+k, dim, p=1)
    for n in (0..7): print(Trow(n, 9))

Formula

We say a sequence R is Jacobi generated by the sequences U and V if R are the coefficients of the series expansion of the Jacobi continued fraction, recursively defined by m = 1 - V(k)*x - U(k)*x^p/m, starting m = 1 and terminating with 1/m, k iterating downwards from a given length to 1. p is some integer (in the classic case p = 2). R is Stieltjes generated if it is Jacobi generated with V(k) = 0 for all k.
In this array the rows are Stieltjes generated with p = 1 from the sequence s(j) = n + j, j >= 0. T(n, k) = A(n)[k] for n >= 0 and k >= 0.
Showing 1-2 of 2 results.