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 11 results. Next

A293266 Coefficients in asymptotic expansion of sequence A096161 and A161779.

Original entry on oeis.org

1, 0, 1, 2, 7, 28, 121, 587, 3205, 19201, 123684, 850873, 6248839, 48948805, 407666212, 3594074850, 33405529547, 326310068618, 3342124657507, 35827145094057, 401325346421766, 4689964771177970, 57081316456694665, 722295766109273335, 9486188532177356598
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 04 2017

Keywords

Examples

			A096161(n) / n! ~ 1 + 1/n^2 + 2/n^3 + 7/n^4 + 28/n^5 + 121/n^6 + ...
A161779(n) / n! ~ 1 + 1/n^2 + 2/n^3 + 7/n^4 + 28/n^5 + 121/n^6 + ...
		

Crossrefs

A110143 Row sums of triangle A110141.

Original entry on oeis.org

1, 1, 4, 11, 43, 161, 901, 5579, 43206, 378360, 3742738, 40853520, 488029621, 6323154547, 88308425755, 1322120265238, 21122364398761, 358647945023885, 6449299885654827, 122436442904193940, 2447046870232798369, 51358050784584629338, 1129314001779283063606
Offset: 0

Views

Author

Paul D. Hanna, Jul 14 2005

Keywords

Comments

Row n of triangle A110141 lists the denominators of unit fraction coefficients of the products of {c_k}, in ascending order by indices of {c_k}, in the coefficient of x^n in exp(Sum_{k>=1} c_k/k*x^k). There are A000041(n) terms in row n of triangle A110141.
Also, number of orbits of Sym(n)^2 where Sym_n acts by conjugation. Compare the MathOverflow discussion, also Bogaerts-Dukes 2014, and A241584, A241585. - Peter J. Dukes, May 12 2014
Number of isomorphism classes of n-fold coverings of a connected graph with circuit rank 2 [Kwak and Lee]. - Álvar Ibeas, Mar 25 2015

References

  • P. A. MacMahon, The expansion of determinants and permanents in terms of symmetric functions, in Proc. ICM Toronto (ed. J. C. Fields), Toronto University Press, 1924, vol 1, 319-330.
  • J. H. Kwak and J. Lee, Enumeration of graph coverings, surface branched coverings and related group theory, in Combinatorial and Computational Mathematics (Pohang, 2000), ed. S. Hong et al., World Scientific, Singapore 2001, pp. 97-161. Appears to contain this sequence in Table 2. [Added by N. J. A. Sloane, Nov 12 2009]

Crossrefs

Programs

  • Maple
    # Using a function from Alois P. Heinz in A279038:
    b:= proc(n, i) option remember; `if`(n=0, [1],
          `if`(i<1, [], [seq(map(x-> x*i^j*j!,
          b(n-i*j, i-1))[], j=0..n/i)]))
        end:
    seq(add(i, i=b(n$2)), n=0..22); # Peter Luschny, Dec 19 2016
  • Mathematica
    Table[Total[Apply[Times, Tally[#]/.{a_Integer,b_}->a^b b!]& /@ IntegerPartitions[n]],{n,0,21}] (* Wouter Meeussen, Oct 17 2014 *)
    b[n_, i_] := b[n, i] = If[n == 0, {1}, If[i < 1, {}, Flatten[ Table[ Map[ #*i^j*j!&, b[n-i*j, i-1]], {j, 0, n/i}]]]]; Table[Sum[i, {i, b[n, n]}], {n, 0, 22}] (* Jean-François Alcover, Jul 10 2017, after Alois P. Heinz *)
    nmax = 25; CoefficientList[Series[Product[Sum[k!*j^k*x^(j*k), {k, 0, nmax/j}], {j, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 08 2019 *)
    m = 30; CoefficientList[Series[Product[-Gamma[0, -1/(x^j*j)] * Exp[-1/(x^j*j)], {j, 1, m}] / (x^(m*(m + 1)/2)*m!), {x, 0, m}], x] (* Vaclav Kotesovec, Dec 07 2020 *)
  • Sage
    def A110143(n):
        return sum(p.aut() for p in Partitions(n))
    [A110143(n) for n in range(9)]
    # Álvar Ibeas, Mar 26 2015

Formula

G.f.: B(x)*B(2*x^2)*B(3*x^3)*..., where B(x) is g.f. of A000142. - Vladeta Jovovic, Feb 18 2007
a(n) ~ n! * (1 + 2/n^2 + 5/n^3 + 23/n^4 + 106/n^5 + 537/n^6 + 3143/n^7 + 20485/n^8 + 143747/n^9 + 1078660/n^10), for coefficients see A279819. - Vaclav Kotesovec, Mar 16 2015

A096162 Let n be a number partitioned as n = b_1 + 2*b_2 + ... + n*b_n; then T(n) = (b_1)! * (b_2)! * ... (b_n)!. Irregular triangle read by rows, T(n, k) for n >= 1 and 1 <= k <= A000041(n).

Original entry on oeis.org

1, 1, 2, 1, 1, 6, 1, 1, 2, 2, 24, 1, 1, 1, 2, 2, 6, 120, 1, 1, 1, 2, 2, 1, 6, 6, 4, 24, 720, 1, 1, 1, 1, 2, 1, 2, 2, 6, 2, 6, 24, 12, 120, 5040, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 6, 2, 4, 2, 24, 24, 6, 12, 120, 48, 720, 40320, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 6, 6, 2, 2, 2, 2, 6, 24, 6, 12, 4, 24, 120
Offset: 1

Views

Author

Alford Arnold, Jun 20 2004

Keywords

Comments

The partitions of number n are grouped by increasing length and in reverse lexical order for partitions of the same length.
This sequence is in the Abramowitz-Stegun ordering, see A036036. - Hartmut F. W. Hoft, Apr 25 2015

Examples

			Illustrating the formula:
1 1 2 1 3 6 1 4 6 12 24 ... A036038
1 1 1 1 3 1 1 4 3  6  1 ... A036040
so
1 1 2 1 1 6 1 1 2  2 24 ... this sequence.
.
From _Hartmut F. W. Hoft_, Apr 25 2015: (Start)
The sequence as a structured triangle. The column headings indicate the number of elements in the underlying partitions. Brackets indicate groups of the products of factorials for all partitions of the same length when there is more than one partition.
     1   2        3        4     5    6
1:   1
2:   1   2
3:   1   1        6
4:   1  [1 2]     2       24
5:   1  [1 1]    [2 2]     6    120
6:   1  [1 1 2]  [2 1 6]  [6 4]  24  720
The partitions, their multiplicities and factorial products associated with the five entries in row n = 4 are:
partitions:         {4}, [{3, 1}, {2, 2}], {2, 1, 1}, {1, 1, 1, 1}
multiplicities:      1,  [{1, 1},  2],     {1, 2},     4
factorial products:  1!, [1!*1!, 2!],      1!*2!,      4!
(End)
		

References

  • Abramowitz and Stegun, Handbook of Mathematical Functions, p. 831, column "M_1" divided by "M_3."

Crossrefs

Row sums in A096161.
Row lengths in A000041.

Programs

  • Mathematica
    (* function a096162[ ] computes complete rows of the triangle *)
    row[n_] := Map[Apply[Times, Map[Factorial, Last[Transpose[Tally[#]]]]]&, GatherBy[IntegerPartitions[n], Length], {2}]
    triangle[n_] := Map[row, Range[n]]
    a096162[n_] := Flatten[triangle[n]]
    Take[a096162[9],90] (* data *)  (*Hartmut F. W. Hoft, Apr 25 2015 *)
  • SageMath
    from collections import Counter
    def A096162_row(n):
        h = lambda p: product(map(factorial, Counter(p).values()))
        return [h(p) for k in (0..n) for p in Partitions(n, length=k)]
    for n in (1..9): print(A096162_row(n)) # Peter Luschny, Nov 01 2019

Formula

T(n, k) = A036038(n,k) / A036040(n,k).
Appears to be n! / A130561(n); e.g., 4! / (24,24,12,12,1) = (1,1,2,2,24). - Tom Copeland, Nov 12 2017

Extensions

Edited and extended by Christian G. Bower, Jan 17 2006

A120774 Number of ordered set partitions of [n] where equal-sized blocks are ordered with increasing least elements.

Original entry on oeis.org

1, 1, 2, 8, 31, 147, 899, 5777, 41024, 322488, 2749325, 25118777, 245389896, 2554780438, 28009868787, 323746545433, 3933023224691, 49924332801387, 661988844566017, 9138403573970063, 131043199040556235, 1949750421507432009, 30031656711776544610
Offset: 0

Views

Author

Alford Arnold, Jul 12 2006

Keywords

Comments

Old name was: Row sums of A179233.
a(n) is the number of ways to linearly order the blocks in each set partition of {1,2,...,n} where two blocks are considered identical if they have the same number of elements. - Geoffrey Critzer, Sep 29 2011

Examples

			A179233 begins 1; 1; 1 1; 6 1 1; 8 3 18 1 1 ... with row sums 1, 1 2 8 31 147 ...
a(3) = 8: 123, 1|23, 23|1, 2|13, 13|2, 3|12, 12|3, 1|2|3. - _Alois P. Heinz_, Apr 27 2017
		

Crossrefs

Row sums of A179233, A285824.
Main diagonal of A327244.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(n=0 or i=1,
          (p+n)!/n!, add(b(n-i*j, i-1, p+j)*combinat
          [multinomial](n, n-i*j, i$j)/j!^2, j=0..n/i))
        end:
    a:= n-> b(n$2, 0):
    seq(a(n), n=0..25);  # Alois P. Heinz, Apr 27 2017
  • Mathematica
    f[{x_,y_}]:= x!^y y!;   Table[Total[Table[n!,{PartitionsP[n]}]/Apply[Times,Map[f,Map[Tally,Partitions[n]],{2}],2] * Apply[Multinomial,Map[Last,Map[Tally,Partitions[n]],{2}],2]],{n,0,20}]  (* Geoffrey Critzer, Sep 29 2011 *)

Extensions

Leading 1 inserted, definition simplified by R. J. Mathar, Sep 28 2011
a(15) corrected, more terms, and new name (using Geoffrey Critzer's comment) from Alois P. Heinz, Apr 27 2017

A161779 The sequence of factorials convolved with all its regularly "aerated" variants.

Original entry on oeis.org

1, 1, 3, 8, 30, 133, 768, 5221, 41302, 369170, 3677058, 40338310, 483134179, 6271796072, 87709287104, 1314511438945, 21017751750506, 357102350816602, 6424883282375340, 122025874117476166, 2439726373093186274, 51220112287152570828, 1126575412217509969515
Offset: 0

Views

Author

Gary W. Adamson, Jun 19 2009

Keywords

Comments

Essentially a duplicate of A096161: 1, followed by A096161.
Convolve A000142 = 1,1,2,6,24,... with 1,0,1,0,2,0,6,0,24,.. and with 1,0,0,1,0,0,2,0,0,6,0,0,24,0,0,.. and with 1,0,0,0,1,0,0,0,2,0,0,0,6,... etc.

Examples

			Let the partial products = a, a*b, a*b*c,..., with the first few rows =
(1, 1, 2, 6, 24, 120,...) = a
(1, 1, 3, 7, 28, 128,...) = a*b
(1, 1, 3, 8, 29, 131,...) = a*b*c
(1, 1, 3, 8, 30, 132,...) = a*b*c*d
...converging to A161779
		

Crossrefs

Cf. A096161, row sums of A333144.

Programs

  • Maple
    read("transforms3") ; read("transforms") ; A161779 := proc(N) local a000142,res,n,j ; a000142 := [seq(n!,n=0..N)] ; res := [seq(op(n,a000142),n=1..N)] ; for j from 1 to N do res := CONV( res, AERATE(a000142,j)) ; od: [seq(op(n,res),n=1..N)] end: A161779(30) ; # R. J. Mathar, Jun 23 2009
    # second Maple program:
    b:= proc(n, i) option remember; `if`(n=0 or i=1, n!,
          add(b(n-i*j, i-1)*j!, j=0..n/i))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..25);  # Alois P. Heinz, Oct 03 2018, revised, Mar 05 2024
  • Mathematica
    b[n_, i_] := b[n, i] = If[i>n, 0, If[Mod[n, i] == 0, (n/i)!, 0] + Sum[j! b[n - i j, i + 1], {j, 0, n/i}]];
    a[n_] := If[n == 0, 1, b[n, 1]];
    a /@ Range[0, 25] (* Jean-François Alcover, Feb 04 2020, after Alois P. Heinz *)

Formula

a(n) = A096161(n) for n >= 1. - R. J. Mathar, Jun 26 2009
a(n) ~ n! * (1 + 1/n^2 + 2/n^3 + 7/n^4 + 28/n^5 + 121/n^6 + 587/n^7 + 3205/n^8 + 19201/n^9 + 123684/n^10), for coefficients see A293266. - Vaclav Kotesovec, Oct 04 2017

Extensions

Extended by R. J. Mathar, Jun 23 2009

A309619 a(n) = Sum_{k=0..floor(n/2)} k! * (n - 2*k)!.

Original entry on oeis.org

1, 1, 3, 7, 28, 128, 754, 5178, 41124, 368220, 3670872, 40290744, 482716896, 6267697920, 87664818960, 1313983544400, 21010949076960, 357007805477280, 6423473819220480, 122003441554176000, 2439346762501367040, 51213306647556506880, 1126446562222595147520
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 10 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 25; CoefficientList[Series[Sum[k!*x^k, {k, 0, nmax}]*Sum[k!*x^(2*k), {k, 0, nmax}], {x, 0, nmax}], x]
    Table[Sum[k!*(n-2*k)!, {k, 0, Floor[n/2]}], {n, 0, 25}]
  • PARI
    a(n) = sum(k=0, n\2, k! * (n - 2*k)!); \\ Michel Marcus, Dec 08 2020

Formula

G.f.: B(x)*B(x^2), where B(x) is g.f. of A000142.
a(n) ~ n! * (1 + 1/n^2 + 1/n^3 + 3/n^4 + 13/n^5 + 57/n^6 + 271/n^7 + 1467/n^8 + 8905/n^9 + 58965/n^10 + ...), for coefficients see A326984.

A326986 G.f.: B(x)*B(x^2)*B(x^3)*..., where B(x) is g.f. of A000312.

Original entry on oeis.org

1, 1, 5, 29, 266, 3163, 46994, 827107, 16828741, 388308078, 10017853262, 285720195351, 8926575094978, 303172417424680, 11121259586618456, 438207141286916539, 18458204444260001120, 827690809585441201775, 39365349178064541861252, 1979267564496263599093676
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 10 2019

Keywords

Crossrefs

Programs

  • Maple
    B:= proc(n) option remember; n^n end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i=1,
          B(n), add(b(j, 1)*b(n-i*j, i-1), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..20);  # Alois P. Heinz, Aug 23 2019
  • Mathematica
    nmax = 20; CoefficientList[Series[Product[1+Sum[k^k*x^(j*k), {k, 1, nmax/j}], {j, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ n^n.

A126787 G.f.: B(x)*B(2!*x^2)*B(3!*x^3)*..., where B(x) is g.f. of A000142.

Original entry on oeis.org

1, 1, 4, 14, 66, 308, 1888, 12240, 95640, 827904, 8106960, 87387264, 1035645312, 13316300928, 184988692800, 2756878875648, 43888205438208, 742943286892800, 13326434312808960, 252448071959572992, 5036116692383428608, 105523926692032447488
Offset: 0

Views

Author

Vladeta Jovovic, Feb 18 2007

Keywords

Comments

Take each Ferrers diagram of the partitions of n, label(linearly order) the dots within each row, then linearly order any of the rows that are of equal length. - Geoffrey Critzer, Mar 21 2009

Crossrefs

Programs

  • Maple
    B:= proc(n) option remember; local x; unapply(`if`(n<=0, 1, B(n-1)(x)+ n! *x^n), x) end: BB:= proc(n) local x, d; unapply(convert(series(mul(B(floor(n/d))(d!*x^d), d=1..n), x, n+1), polynom), x) end: a:= n-> coeff(BB(n)(x), x, n): seq(a(n), n=0..25); # Alois P. Heinz, Sep 25 2008
    # second Maple program:
    b:= proc(n, i) option remember; `if`(n=0 or i=1, n!,
          add(b(n-i*j, i-1)*j!*i!^j, j=0..n/i))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);  # Alois P. Heinz, Oct 02 2017
  • Mathematica
    CoefficientList[Series[Product[Sum[x^(n*k) n!^k*k!, {k, 0, 20}], {n, 1, 20}], {x, 0, 20}], x] (* Geoffrey Critzer, Mar 21 2009 *)

Formula

a(n) ~ 2*n! * (1 + 1/(2*n) + 3/n^2 + 13/n^3 + 82/n^4 + 587/n^5 + 4966/n^6). - Vaclav Kotesovec, Mar 16 2015

Extensions

More terms from Alois P. Heinz, Sep 25 2008

A179233 Irregular triangle T(n,k) = A049019(n,k)/A096162(n,k) read along rows, 1<=k <= A000041(n).

Original entry on oeis.org

1, 1, 1, 1, 6, 1, 1, 8, 3, 18, 1, 1, 10, 20, 30, 45, 40, 1, 1, 12, 30, 10, 45, 360, 15, 80, 270, 75, 1, 1, 14, 42, 70, 63, 630, 210, 315, 140, 2520, 420, 175, 1050, 126, 1, 1, 16, 56, 112, 35, 84, 1008, 1680, 630, 840, 224, 5040, 1680
Offset: 1

Views

Author

Alford Arnold, Jul 08 2010

Keywords

Comments

Each row n of A049019, of A096162 and of the triangle here has A000041(n) entries.

Examples

			A049019(.,.) begins 1; 1; 2, 1; 6, 6, 1; 8, 6, 36, 24, ...
A096162(.,.) begins 1; 1; 2, 1; 1, 6, 1; 1, 2, 2, 24 ...
so
T(.,.) begins ..... 1; 1; 1, 1; 6, 1, 1; 8, 3, 18, 1 ...
		

Crossrefs

Formula

T(n,k) = A049019(n,k) / A096162(n,k) = A048996(n,k) * A036040(n,k).
Sum_{k=1..A000041(n)} T(n,k) = A120774(n).

Extensions

Extended, and bivariate indices restored - R. J. Mathar, Jul 13 2010

A179236 Irregular triangle T(n,k) = A096162(n,k)* A036040(n,k)* A048996(n,k)*A098546(n,k)* A178886(n,k) read by rows, 1<=k<=A000041(n).

Original entry on oeis.org

1, 2, 2, 6, 36, 6, 24, 192, 72, 432, 24, 120, 1200, 2400, 3600, 5400, 4800, 120, 720, 8640, 21600, 7200, 32400, 259200, 10800, 57600, 194400, 54000, 720, 5040, 70560, 211680, 352800, 317520, 3175200, 1058400, 1587600, 705600, 12700800, 2116800, 882000, 5292000, 635040, 5040, 40320, 645120, 2257920, 4515840
Offset: 1

Views

Author

Alford Arnold, Jul 04 2010

Keywords

Examples

			The factor sequences begin
1..1..2..1..1..6
1..1..1..1..3..1
1..1..1..1..2..1
1..2..1..3..3..1
1..1..1..2..2..1
so the present sequence begins
1..2..2..6..36..6
		

Crossrefs

Cf. A000041 (row lengths) A096161 A000110 A000079 A098545 A000522 A179235 (row sums)
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