login
Number of nonempty subsets of {1,2,...,n} in which exactly 5/6 of the elements are <= (n-1)/3.
1

%I #7 Jul 23 2018 02:45:03

%S 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,11,12,13,78,84,90,315,336,357,952,1008,

%T 1064,2394,2520,2646,5502,5775,6049,13409,14124,14850,39600,42042,

%U 44550,135135,144144,153439,464464,495495,527527

%N Number of nonempty subsets of {1,2,...,n} in which exactly 5/6 of the elements are <= (n-1)/3.

%H Robert Israel, <a href="/A048015/b048015.txt">Table of n, a(n) for n = 1..6126</a>

%p f:= proc(n) local k,m;

%p m:= floor((n-1)/3);

%p add(binomial(m,5*k/6)*binomial(n-m,k/6),k=6..m*6/5,6);

%p end proc:

%p map(f, [$1..100]); # _Robert Israel_, Jul 23 2018

%K nonn

%O 1,16

%A _Clark Kimberling_