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A110143 Row sums of triangle A110141. 10
1, 1, 4, 11, 43, 161, 901, 5579, 43206, 378360, 3742738, 40853520, 488029621, 6323154547, 88308425755, 1322120265238, 21122364398761, 358647945023885, 6449299885654827, 122436442904193940, 2447046870232798369, 51358050784584629338, 1129314001779283063606 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

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]

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..450

Mathieu Bogaerts and Peter Dukes, Semidefinite programming for permutation codes, Discrete Math. 326 (2014), 34--43. MR3188985.

J. B. Geloun, S. Ramgoolam, Counting Tensor Model Observables and Branched Covers of the 2-Sphere, arXiv:1307.6490 [hep-th], 2013.

J. H. Kwak and J. Lee, Isomorphism classes of graph bundles. Can. J. Math., 42(4), 1990, pp. 747-761.

MathOverflow, A general formula for the number of conjugacy classes of S_n×S_n acted on by S_n [From Peter Dukes, May 12 2014]

Igor Pak, Greta Panova, Damir Yeliussizov, On the largest Kronecker and Littlewood-Richardson coefficients, arXiv:1804.04693 [math.CO], 2018.

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

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 *)

PROG

(Sage) sum([p.aut() for p in Partitions(n)]) # Álvar Ibeas, Mar 26 2015

CROSSREFS

Cf. A110141, A000041, A057005, A096161, A241584, A241585, A279819.

Third column of A160449.

Sequence in context: A323792 A241584 A176576 * A149279 A149280 A149281

Adjacent sequences:  A110140 A110141 A110142 * A110144 A110145 A110146

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 14 2005

STATUS

approved

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Last modified April 21 10:30 EDT 2019. Contains 322328 sequences. (Running on oeis4.)