A002875 - OEIS

A002875

Number of partitions of {1..3n} that are invariant under a permutation consisting of n 3-cycles with k orbits of blocks, maximized over k.
(Formerly M1300 N0498)

1, 2, 4, 24, 128, 880, 7440, 61208, 632576, 7082880, 78292160, 1008230080, 14096343360, 195581978592, 2892504206592, 48536902237824, 810231258403840, 13494468138464768, 258148312376048640, 5036531225050276352, 98081251585174208512, 1967179816262245736448

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OFFSET

0,2

REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..21.

Victor Meally, Comparison of several sequences given in Motzkin's paper "Sorting numbers for cylinders...", letter to N. J. A. Sloane, N. D.

T. S. Motzkin, Sorting numbers for cylinders and other classification numbers, in Combinatorics, Proc. Symp. Pure Math. 19, AMS, 1971, pp. 167-176. [Annotated, scanned copy]

OEIS Wiki, Sorting numbers

Index entries for sequences related to sorting

MATHEMATICA

aList[n_] := Max /@ CoefficientList[Exp[y ((Exp[3x]-1)/3 + Exp[x]-1)] + O[x]^n, {x, y}] (Range[n]-1)!;

CROSSREFS

Maximum row values of A395327.

Cf. A000262, A001861, A002870, A002871, A002872, A002873, A002874, A036073, A294201.

A294202 has a similar definition based on partition blocks rather than their orbits.

Sequence in context: A371892 A164313 A087981 * A330504 A330511 A110491

Adjacent sequences: A002872 A002873 A002874 * A002876 A002877 A002878

KEYWORD

nonn