This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A210116 #7 Mar 31 2012 20:17:50
%S A210116 7776,311,51,16,7,4,3,3,2,3,3,4,5,8,11,16,25,40,66,110,187,325,574,
%T A210116 1032,1885,3492,6557,12467,23988,46667,91731,182078,364734,736972,
%U A210116 1501318,3082136,6374007,13273719,27825438,58697777,124566798
%N A210116 Floor of the expected value of number of trials until exactly five cells are empty in a random distribution of n balls in n cells.
%C A210116 Also floor of the expected value of number of trials until we have n-5 distinct symbols in a random sequence on n symbols of length n. A055775 corresponds to zero cells empty.
%D A210116 W. Feller, An Introduction to Probability Theory and its Applications, 2nd ed, Wiley, New York, 1965, (2.4) p. 92. (Occupancy problems)
%H A210116 W. Bomfim, <a href="/A210116/b210116.txt">Table of n, a(n) for n = 6..100</a>
%F A210116 With m = 5, a(n) = floor(n^n/(binomial(n,m)*_Sum{v=0..n-m-1}((-1)^v*binomial(n-m,v)*(n-m-v)^n)))
%e A210116 For n=6, there are 6^6 = 46656 sequences on 6 symbols of length 6. Only 6 sequences has a unique symbol, so a(6) = floor(46656/6) = 7776.
%Y A210116 Cf. A055775, A209899, A209900, A210112, A210113, A210114, A210115.
%K A210116 nonn
%O A210116 6,1
%A A210116 _Washington Bomfim_, Mar 18 2012