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%I #9 May 05 2016 08:43:50
%S 0,0,9,31,70,130,215,329,476,660,885,1155,1474,1846,2275,2765,3320,
%T 3944,4641,5415,6270,7210,8239,9361,10580,11900,13325,14859,16506,
%U 18270,20155,22165,24304,26576,28985,31535,34230,37074,40071,43225,46540,50020,53669
%N Number of orbits of Aut(Z^7) as function of the infinity norm n of the representative lattice point of the orbit, when the cardinality of the orbit is equal to 26880.
%H Colin Barker, <a href="/A266397/b266397.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F From _Colin Barker_, Dec 29 2015: (Start)
%F a(n) = (4*n^3+3*n^2-37*n+30)/6.
%F a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4) for n>4.
%F G.f.: x^3*(9-5*x) / (1-x)^4.
%F (End)
%o (PARI) concat(vector(2), Vec(x^3*(9-5*x)/(1-x)^4 + O(x^50))) \\ _Colin Barker_, May 05 2016
%Y Number of orbits of Aut(Z^7) as function of the infinity norm A000579, A154286, A102860, A002412, A045943, A115067, A008586, A008585, A005843, A001477, A000217.
%K nonn,easy
%O 1,3
%A _Philippe A.J.G. Chevalier_, Dec 29 2015
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