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A054947 Enumerates pairs consisting of a strongly connected labeled tournament and an arbitrary labeled tournament. 5
1, 0, 16, 1536, 557056, 731381760, 3517947314176, 63491024068018176, 4399839304395507367936, 1190389701200990489133711360, 1270450770186900638201337522159616, 5381052721259860098970976735257549602816, 90765718885519516263620106778209295628266110976 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

Miklos Bona, editor, Handbook of Enumerative Combinatorics, CRC Press, 2015, page 428, see b_n.

LINKS

Table of n, a(n) for n=1..13.

V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.

MAPLE

A054947 := proc(n)

    option remember;

    if n = 1 then

        1;

    else

        2^(n*(n-1))-add(binomial(n, t)*2^((n-1)*(n-t))*procname(t), t=1..n-1) ;

    end if;

end proc: # R. J. Mathar, May 10 2016

MATHEMATICA

a[1] = 1; a[n_] := a[n] = 2^(n(n-1)) - Sum[Binomial[n, j] 2^((n-1)(n-j)) a[j], {j, 1, n-1}];

Array[a, 13] (* Jean-Fran├žois Alcover, Aug 27 2019 *)

PROG

(PARI) seq(n)={my(v=vector(n)); v[1]=1; for(n=2, #v, v[n]=2^(n*(n-1))-sum(j=1, n-1, binomial(n, j)*2^((n-1)*(n-j))*v[j])); v} \\ Andrew Howroyd, Sep 09 2018

CROSSREFS

Sequence in context: A178024 A221613 A266156 * A071900 A321247 A145406

Adjacent sequences:  A054944 A054945 A054946 * A054948 A054949 A054950

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 24 2000

EXTENSIONS

More terms from Vladeta Jovovic, Mar 11 2003

STATUS

approved

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Last modified April 10 11:35 EDT 2021. Contains 342845 sequences. (Running on oeis4.)