login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A054947 Enumerates pairs consisting of a strongly connected labeled tournament and an arbitrary labeled tournament. 5

%I

%S 1,0,16,1536,557056,731381760,3517947314176,63491024068018176,

%T 4399839304395507367936,1190389701200990489133711360,

%U 1270450770186900638201337522159616,5381052721259860098970976735257549602816,90765718885519516263620106778209295628266110976

%N Enumerates pairs consisting of a strongly connected labeled tournament and an arbitrary labeled tournament.

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

%H V. A. Liskovets, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL3/LISK/Derseq.html">Some easily derivable sequences</a>, J. Integer Sequences, 3 (2000), #00.2.2.

%p A054947 := proc(n)

%p option remember;

%p if n = 1 then

%p 1;

%p else

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

%p end if;

%p end proc: # _R. J. Mathar_, May 10 2016

%t 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}];

%t Array[a, 13] (* _Jean-Fran├žois Alcover_, Aug 27 2019 *)

%o (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

%K nonn,easy

%O 1,3

%A _N. J. A. Sloane_, May 24 2000

%E More terms from _Vladeta Jovovic_, Mar 11 2003

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 16 12:38 EDT 2021. Contains 343947 sequences. (Running on oeis4.)