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%I A055671 #11 Aug 28 2016 18:18:34
%S A055671 0,0,24,96,0,144,0,192,0,0,0,288,0,336,0,0,0,432,0,480,0,0,0,576,0,0,
%T A055671 0,0,0,720,0,768,0,0,0,0,0,912,0,0,0,1008,0,1056,0,0,0,1152,0,0,0,0,0,
%U A055671 1296,0,0,0,0,0,1440,0,1488,0,0,0,0,0,1632,0,0,0,1728,0,1776,0,0,0,0,0
%N A055671 Number of prime Hurwitz quaternions of norm n.
%D A055671 L. E. Dickson, Algebras and Their Arithmetics, Dover, 1960, Section 91.
%H A055671 R. J. Mathar, <a href="/A055671/b055671.txt">Table of n, a(n) for n = 0..10000</a>
%F A055671 a(n) = number of vectors of norm n in D_4 lattice (A004011) if n is a prime, otherwise a(n) = 0.
%t A055671 a[p_?PrimeQ] := Reduce[ a^2 + b^2 + c^2 + d^2 == 4p, {a, b, c, d}, Integers] // Length; a[_] = 0; Table[ a[n], {n, 0, 78}] (* _Jean-François Alcover_, Oct 03 2012 *)
%Y A055671 Cf. A055669-A055672.
%K A055671 nonn,easy,nice
%O A055671 0,3
%A A055671 _N. J. A. Sloane_, Jun 09 2000
%E A055671 More terms from Lambert Klasen (Lambert.Klasen(AT)gmx.net), Jun 10 2005

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