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.

Previous Showing 31-39 of 39 results.

A205543 Logarithmic derivative of the Bell numbers (A000110).

Original entry on oeis.org

1, 3, 10, 39, 171, 822, 4271, 23759, 140518, 878883, 5789015, 40019058, 289513303, 2186421919, 17199606090, 140662816543, 1193865048363, 10499107480518, 95528651305671, 898071593401559, 8712429618413678, 87118795125708283, 896925422648691735
Offset: 1

Views

Author

Paul D. Hanna, Jan 28 2012

Keywords

Comments

a(n) = number of indecomposable partitions (A074664) of [n+3] in which n+3 lies in a doubleton block (see Link). - David Callan, Oct 08 2014

Examples

			L.g.f.: L(x) = x + 3*x^2/2 + 10*x^3/3 + 39*x^4/4 + 171*x^5/5 + 822*x^6/6 +...
where exponentiation yields the o.g.f. of the Bell numbers:
exp(L(x)) = 1 + x + 2*x^2 + 5*x^3 + 15*x^4 + 52*x^5 + 203*x^6 + 877*x^7 +...
which equals the series:
exp(L(x)) = 1 + x/(1-x) + x^2/((1-x)*(1-2*x)) + x^3/((1-x)*(1-2*x)*(1-3*x)) +...
		

Crossrefs

Cf. A000110.

Programs

  • PARI
    {a(n)=n*polcoeff(log(sum(m=0,n, x^m/prod(k=1,m, 1-k*x +x*O(x^n)))),n)}

Formula

L.g.f.: log( Sum_{n>=0} x^n / Product_{k=1..n} (1 - k*x) ).

A130167 Another version of triangle in A127743.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 2, 1, 0, 6, 5, 3, 1, 0, 22, 16, 9, 4, 1, 0, 92, 60, 31, 14, 5, 1, 0, 426, 252, 120, 52, 20, 6, 1, 0, 2146, 1160, 510, 209, 80, 27, 7, 1, 0, 11624, 5776, 2348, 904, 335, 116, 35, 8, 1, 0, 67146, 30832, 11610, 4184, 1481, 507, 161, 44, 9, 1
Offset: 0

Views

Author

Philippe Deléham, Aug 03 2007

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows given by [0,1,1,2,1,3,1,4,1,5,1,6,1,...] DELTA [1,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938.
Modulo 2, this sequence gives A106344. - Philippe Deléham, Dec 18 2008
A154380*A130595 as infinite lower triangular matrices. - Philippe Deléham, Jan 13 2009

Examples

			Triangle begins:
  1;
  0,  1;
  0,  1,  1;
  0,  2,  2,  1;
  0,  6,  5,  3,  1;
  0, 22, 16,  9,  4,  1;
  0, 92, 60, 31, 14,  5,  1; ...
		

Crossrefs

Cf. A074664.

Formula

Sum_{k=0..n} T(n,k) = A000110(n).

A321960 Array of sequences read by descending antidiagonals, A(n) the Jacobi square of the sequence n, n+1, n+2, ....

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 2, 1, 0, 5, 6, 3, 1, 0, 15, 22, 12, 4, 1, 0, 52, 92, 57, 20, 5, 1, 0, 203, 426, 303, 116, 30, 6, 1, 0, 877, 2146, 1752, 744, 205, 42, 7, 1, 0, 4140, 11624, 10845, 5140, 1535, 330, 56, 8, 1, 0, 21147, 67146, 71139, 37676, 12300, 2820, 497, 72, 9, 1
Offset: 0

Views

Author

Peter Luschny, Dec 27 2018

Keywords

Comments

For definitions and comments see A321964.

Examples

			First few rows of the array start:
[0] 1, 0,  0,   0,    0,     0,      0,       0,        0, ... A000007
[1] 1, 1,  2,   5,   15,    52,    203,     877,     4140, ... A000110
[2] 1, 2,  6,  22,   92,   426,   2146,   11624,    67146, ... A074664
[3] 1, 3, 12,  57,  303,  1752,  10845,   71139,   491064, ... A321959
[4] 1, 4, 20, 116,  744,  5140,  37676,  290224,  2334300, ...
[5] 1, 5, 30, 205, 1535, 12300, 103975,  918785,  8434740, ...
[6] 1, 6, 42, 330, 2820, 25662, 245358, 2443272, 25188870, ...
[7] 1, 7, 56, 497, 4767, 48496, 516761, 5719399, 65369136, ...
Seen as triangle:
[0] 1;
[1] 0,   1;
[2] 0,   1,    1;
[3] 0,   2,    2,    1;
[4] 0,   5,    6,    3,   1;
[5] 0,  15,   22,   12,   4,   1;
[6] 0,  52,   92,   57,  20,   5,  1;
[7] 0, 203,  426,  303, 116,  30,  6, 1;
[8] 0, 877, 2146, 1752, 744, 205, 42, 7, 1;
		

Crossrefs

Rows of array: A000007, A000110, A074664, A321959.
Columns include: A002378, A033445. Row sums of triangle: A321958.
Cf. A321964.

Programs

  • Maple
    # The function JacobiSquare is defined in A321964.
    s := n -> [seq(n+k, k = 0..9)]: Trow := n -> JacobiSquare(s(n)):
    for n from 0 to 7 do lprint(Trow(n)) od;
  • Mathematica
    nmax = 10;
    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];
    JacobiSquare[a_, p_: 2] := Module[{cf, ser}, cf = JacobiCF[a, a, p]; ser = Series[cf, {x, 0, Length[a]}]; CoefficientList[ser, x]];
    s[n_] := Table[n + k, {k, 0, nmax}];
    row[n_] := row[n] = JacobiSquare[s[n]];
    T[, 0] = 1; T[0, ] = 0; T[n_, k_] := row[n][[k + 1]];
    Table[T[n - k, k], {n, 0, nmax}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Jul 13 2019, after Peter Luschny in A321964 *)
  • Sage
    def JacobiCF(a, b, dim, p=2):
        m = 1
        for k in range(dim-1, -1, -1):
            m = 1 - b(k)*x - a(k)*x^p/m
        return 1/m
    def JacobiGF(a, b, dim, p=2):
        cf = JacobiCF(a, b, dim, p)
        return cf.series(x, dim).list()
    def JacobiSquare(a, dim, p=2):
        cf = JacobiCF(a, a, dim, p)
        return cf.series(x, dim).list()
    def StieltjesGF(a, dim, p=2):
        return JacobiGF(a, lambda n: 0, dim, p)
    def Trow(n): return JacobiSquare(lambda k: n+k, 10)
    for n in (0..4): print(Trow(n))

Formula

T(n, k) = A(n)[k] where A(n) is the Jacobi square of the sequence s(j) = n + j, j >= 0.

A179488 G.f.: A(x) satisfies A(x) = x/(1 - (1-2x)*A( x/(1-2x) )).

Original entry on oeis.org

1, 1, 2, 7, 32, 172, 1052, 7177, 53792, 437992, 3841772, 36060262, 360234512, 3812425912, 42576007352, 500022862357, 6157034292032, 79278216024592, 1064888929532492, 14890014669234922, 216315676347260912
Offset: 1

Views

Author

Paul D. Hanna, Aug 13 2010

Keywords

Examples

			G.f.: A(x) = x + x^2 + 2*x^3 + 7*x^4 + 32*x^5 + 172*x^6 + ...
A(x) = x + x*A(x) + x*A(x)*A(x/(1-2x)) + x*A(x)*A(x/(1-2x))*A(x/(1-4x)) + x*A(x)*A(x/(1-2x))*A(x/(1-4x))*A(x/(1-6x)) + ...
		

Crossrefs

Cf. variants: A074664, A179489.

Programs

  • PARI
    {a(n)=local(A=x+x^2);for(i=1,n,A=x/(1-(1-2*x)*subst(A,x,x/(1-2*x+x^2*O(x^n)))));polcoeff(A,n)}

Formula

G.f.: x/(1 - (1-2*x)*x/(1-2*x - (1-4*x)*x/(1-4*x - (1-6*x)*x/(1-6*x - (1-8*x)*x/(1-8*x - ... (continued fraction).
From Gary W. Adamson, Jul 21 2011: (Start)
a(n) = upper left term of M^(n-1), M = an infinite square production matrix as follows (with the odd integers as the main diagonal):
1, 1, 0, 0, 0, ...
1, 3, 1, 0, 0, ...
1, 1, 5, 1, 0, ...
1, 1, 1, 7, 1, ...
1, 1, 1, 1, 9, ...
... (End)
G.f.: 2/E(0) where E(k) = 1 + 1/(1 + 2*x/(1 - 2*(2*k+3)*x/E(k+1))); (continued fraction, 3-step). - Sergei N. Gladkovskii, Sep 20 2012
G.f.: 1/Q(0) where Q(k) = 1 - x*(2*k+1)/( 1 - x/Q(k+1) ); (continued fraction). - Sergei N. Gladkovskii, Mar 22 2013
G.f.: 1/x - Q(0)/x, where Q(k) = 1 - x/(1 - (2*k+1)*x/Q(k+1) ); (continued fraction). - Sergei N. Gladkovskii, Sep 27 2013

A179489 G.f.: A(x) = x/(1 - (1-3x)*A( x/(1-3x) )).

Original entry on oeis.org

1, 1, 2, 8, 44, 288, 2172, 18516, 175352, 1819868, 20491844, 248417128, 3221797252, 44464876996, 650076797232, 10028658649668, 162695157490644, 2767333692834768, 49221196196394252, 913310582666986596
Offset: 1

Views

Author

Paul D. Hanna, Aug 13 2010

Keywords

Examples

			G.f.: A(x) = x + x^2 + 2*x^3 + 8*x^4 + 44*x^5 + 288*x^6 + ...
A(x) = x + x*A(x) + x*A(x)*A(x/(1-3x)) + x*A(x)*A(x/(1-3x))*A(x/(1-6x)) + x*A(x)*A(x/(1-3x))*A(x/(1-6x))*A(x/(1-9x)) +...
		

Crossrefs

Cf. variants: A074664, A179488.

Programs

  • PARI
    {a(n)=local(A=x+x^2);for(i=1,n,A=x/(1-(1-3*x)*subst(A,x,x/(1-3*x+x^2*O(x^n)))));polcoeff(A,n)}

Formula

G.f.: A(x) = x/(1 - (1-3x)*x/(1-3x - (1-6x)*x/(1-6x - (1-9x)*x/(1-9x - (1-12x)*x/(1-12x - ... (continued fraction).
From Gary W. Adamson, Jul 22 2011: (Start)
a(n) = the upper left term in M^(n-1), M = an infinite square production matrix with the series 3*n-2 as the main diagonal:
1, 1, 0, 0, 0, ...
1, 4, 1, 0, 0, ...
1, 1, 7, 1, 0, ...
1, 1, 1,10, 0, ...
... (End)

A273396 Indecomposable collections of multisets with a total of n objects having entries {1,2,...,k} for some k<=n or INVERTi transform of A255906.

Original entry on oeis.org

0, 1, 3, 9, 39, 201, 1227, 8305, 61383, 487761, 4131819, 37072361, 350644047, 3482957945, 36220558835, 393329507169, 4450157382383, 52354044069009, 639307054297779, 8090092395577625, 105935581968131399, 1433456549698679385, 20018656224312123051
Offset: 0

Views

Author

Mike Zabrocki, May 21 2016

Keywords

Comments

A multiset partition of a multiset S is a set of nonempty multisets whose union is S. The total number of multisets of size n and whose entries have all the values in {1,2,...,k} for some k<=n is given by sequence A255906. A multiset partition is decomposable if there exists a value 1<=dd. A multiset partition is called indecomposable otherwise.

Examples

			a(3) = 9 because there are 16 multiset partitions, 9 of them are indecomposable ({{1},{1},{1}}, {{1},{1,1}}, {{1,1,1}}, {{1},{1,2}}, {{2},{1,2}}, {{1,1,2}}, {{1,2,2}}, {{2},{1,3}}, {{1,2,3}}) and 7 are decomposable ({{1},{1},{2}}, {{1},{2},{2}}, {{1},{2,2}}, {{2},{1,1}}, {{1},{2},{3}}, {{1},{2,3}}, {{3},{1,2}}).
		

References

  • P. A. MacMahon, Combinatory Analysis, vol 1, Cambridge, 1915.

Crossrefs

INVERTi transform of A255906.

A127745 Counts Bell numbers (except for Catalans) associated with the partition number [n].

Original entry on oeis.org

0, 0, 0, 1, 8, 50, 294, 1717, 10194, 62284, 394346, 2597266, 17827166, 127575414, 951411752, 7386583917, 59623674472, 499648882838, 4340548090590, 39033489125836, 362871600781796, 3482858492844510, 34471940635650958, 351444263328831458
Offset: 1

Views

Author

Alford Arnold, Feb 25 2007

Keywords

Comments

A074664 counts the Bell Numbers associated with the partition number [n]. A000108 counts the corresponding Catalan numbers and here we count the remaining Bell numbers associated with the partition number [n].

Examples

			There are 15 Bell objects when n = 4, 14 are also Catalans so a(4) = 1.
There are 52 Bell objects when n = 5, 42 are also Catalans; we know that 5 = 4+1 = 1+4 which accounts for two of the non-Catalan Bells so, a(5) = 52 - 42 - 2 = 8.
		

Crossrefs

Formula

a(n) = A074664(n) - A000108(n-1)

A173050 Triangle, read by rows, given by [0,1,1,1,1,1,1,1,...] DELTA [1,0,1,0,2,0,3,0,4,0,5,0,6,0,...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 3, 1, 0, 5, 10, 6, 1, 0, 14, 36, 31, 10, 1, 0, 42, 135, 156, 77, 15, 1, 0, 132, 518, 771, 534, 169, 21, 1, 0, 429, 2015, 3745, 3451, 1610, 345, 28, 1, 0, 1430, 7906, 17897, 21094, 13569, 4537, 676, 36, 1, 0, 4862, 31195, 84278, 123203, 103986
Offset: 0

Views

Author

Philippe Deléham, Feb 08 2010

Keywords

Examples

			Triangle begins:
  1
  0,  1
  0,  1,  1
  0,  2,  3,  1
  0,  5, 10,  6,  1
  0, 14, 36, 31, 10, 1
  ...
		

Crossrefs

Formula

Sum_{k=0..n} T(n,k) = A074664(n+1).

Extensions

Corrected by Philippe Deléham, Feb 08 2010

A357438 Triangle T(n,k) read by rows, defined by the equation f(x, y) := Sum_{n, k} T(n, k) * y^k * x^n = 1/(1 - x*y - x^2*y*f(x, y+1)).

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 2, 6, 6, 1, 0, 5, 16, 20, 10, 1, 0, 15, 51, 71, 50, 15, 1, 0, 52, 186, 281, 231, 105, 21, 1, 0, 203, 759, 1223, 1114, 616, 196, 28, 1, 0, 877, 3409, 5795, 5701, 3564, 1428, 336, 36, 1, 0, 4140, 16655, 29634, 31011, 21187, 9780
Offset: 1

Views

Author

Michael Somos, Sep 27 2022

Keywords

Comments

Row sums are A000110.

Examples

			Triangle starts:
  1,
  0,   1,
  0,   1,    1,
  0,   1,    3,    1,
  0,   2,    6,    6,    1,
  0,   5,   16,   20,   10,    1,
  0,  15,   51,   71,   50,   15,    1,
  0,  52,  186,  281,  231,  105,   21,  1,
  0, 203,  759, 1223, 1114,  616,  196,  28,  1,
  0, 877, 3409, 5795, 5701, 3564, 1428, 336, 36, 1,
  ...
		

Crossrefs

Programs

  • Mathematica
    T[ n_, k_] := If[n < 0, 0, Coefficient[SeriesCoefficient[ Nest[ 1/(1 - x*y - x^2*y*(#/.y -> y+1))&, 1 + O[x], Ceiling[n/2]], {x, 0, n}], y, k]];
  • PARI
    {T(n, k) = if(n < 0, 0, f = 1 + O(x); forstep(i=1, n, 2, f = 1/(1 - x*y - x^2*y*subst(f, y, y+1))); polcoef(polcoef(f, n), k))};

Formula

f(x, -1) = 1/(1 + x + x^2).
x + x^2*f(x, 2) = 1 - 1/f(x, 1) is g.f. for A074664.
Previous Showing 31-39 of 39 results.