%I A064842
%S A064842 0,2,6,18,36,66,106,162,232,322,430,562,716,898,1106,1346,1616,
%T A064842 1922,2262,2642,3060,3522,4026,4578,5176,5826,6526,7282,8092,8962,
%U A064842 9890,10882,11936,13058,14246,15506,16836,18242,19722,21282,22920
%N A064842 Maximal value of sum([p(i)-p(i+1)]^2,i=1..n), where p(n+1)=p(1), as p 
               ranges over all permutations of {1,2,...,n}.
%D A064842 K. Selkirk, Re-designing the dartboard, Math. Gaz., 60 (1976), 171-178.
%D A064842 V. Mihai, Problem 10725, Amer. Math. Monthly, 108 (March 2001), pp. 272-273.
%H A064842 G. L. Cohen and E. Tonkes, <a href="http://www.combinatorics.org/">Dartboard 
               arrangements</a>, Elect. J. Combin., 8 (No. 2, 2001), #R4.
%F A064842 If n mod 2 = 0 then n^3/3-4*n/3+2 else n^3/3-4*n/3+1.
%e A064842 a(4)=18 because the values of the sum for the permutations of {1,2,3,
               4} are 10 (8 times), 12 (8 times) and 18 (8 times).
%p A064842 a:=proc(n) if n mod 2 = 0 then (n^3-4*n)/3+2 else (n^3-4*n)/3+1 fi end: 
               seq(a(n),n=1..41); (Deutsch)
%Y A064842 Cf. A064843.
%Y A064842 Sequence in context: A066286 A034881 A146345 this_sequence A101695 A014741 
               A016059
%Y A064842 Adjacent sequences: A064839 A064840 A064841 this_sequence A064843 A064844 
               A064845
%K A064842 nonn
%O A064842 1,2
%A A064842 N. J. A. Sloane (njas(AT)research.att.com), Oct 25 2001
%E A064842 Edited by Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 30 2005