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%I #13 Jul 11 2021 03:42:35
%S 1,24,195984,16779168,397998672,4629497040,34417510848,187489533504,
%T 814881802320,2975548760568,9486548517600,27052958750688,
%U 70486228096704,169931081461008,384163595996544,820166650027200,1668890114013264,3249630946490544,6096882726702288
%N Theta series of nonexistent Niemeier lattice of Coxeter number 1.
%D J. H. Conway and N. J. A. Sloane, Sphere Packings, Lattices and Groups, Springer-Verlag, 1988.
%H Andy Huchala, <a href="/A056947/b056947.txt">Table of n, a(n) for n = 0..20000</a>
%F E_12(z)+(24h-c12)*D(12) where D(12) is unique cusp form of weight 12, c12=(2*Pi)^12/(zeta(12)*gamma(12)) and h=1.
%F a(n) = (A029828(n) - 48936*A000594(n))/691. - _Andy Huchala_, Jul 11 2021
%e G.f.: 1 + 24*q + 195984*q^2 + 16779168*q^3 + ...
%o (Sage)
%o d = CuspForms(1, 12).0.q_expansion(20);
%o e =(eisenstein_series_qexp(12,20, normalization='integral'))
%o list(e/691-(48936/691)*d) # _Andy Huchala_, Jul 10 2021
%Y Cf. A029828, A000594.
%K nonn
%O 0,2
%A Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jul 17 2000