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Maximum absolute value of coefficients of characteristic polynomial of M_n, the n X n matrix m_(i,j) = i mod j.
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%I #7 Mar 30 2012 18:39:11

%S 1,1,2,5,47,105,1272,8424,55856,388800,6592492,37965600,1573051680,

%T 10106845824,145938179520,2694653982720,18948491739696,

%U 267048208800000,23293245955795200,466687809894297600,3372079713556377600

%N Maximum absolute value of coefficients of characteristic polynomial of M_n, the n X n matrix m_(i,j) = i mod j.

%e Characteristic polynomial of M_4 is x^4 - 5*x^2 - 2*x^1 + 0*x^0.

%t a[n_] := Max@@Abs/@CoefficientList[CharacteristicPolynomial[Table[Mod[i, j], {i, n}, {j, n}], x], x]

%Y Cf. A078924.

%K nonn

%O 1,3

%A _Benoit Cloitre_, Dec 15 2002