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%I #17 Mar 23 2020 09:16:23
%S 0,0,2,20,204,2604,39990,720600,14913080,348678440,9090909090,
%T 261535698060,8230246567620,281241170407092,10371206370520814,
%U 410525522232055664,17361641481138401520,781282469559318055056
%N Number of sequences of length n with terms from {0,1,...,n-1} such that the sum of terms is 0 modulo n and the i-th term is not i.
%H ArtOfProblemSolving forum, <a href="http://www.artofproblemsolving.com/Forum/viewtopic.php?t=31946">45th IMO Team Selection Test Lincoln, Nebraska</a>
%F For odd n, a(n) = ((n-1)^n-n+1)/n.
%F For even n, a(n) = ((n-1)^n-1)/n.
%F a(n) = floor((n-1)^n / n). - From _Alex Ratushnyak_, Aug 04 2012.
%o (Python)
%o for n in range(1, 33):
%o print((n-1)**n // n, end=',')
%o # from _Alex Ratushnyak_, Aug 04 2012
%Y Cf. A173500
%K nonn
%O 1,3
%A _Max Alekseyev_, Feb 20 2010
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