%I #12 Feb 27 2018 02:58:57
%S 1,-552,7992,460896,-3450504,-88161264,-728085024,-3775195968,
%T -14894175240,-48567693576,-137214605232,-347495426784,-804758753568,
%U -1733365307184,-3511286411328,-6753825302976,-12422812497672,-21971174382288,-37567247938344
%N Coefficients in q-expansion of E_2^2*E_6, where E_2 and E_6 are respectively the Eisenstein series A006352 and A013973.
%H Seiichi Manyama, <a href="/A282595/b282595.txt">Table of n, a(n) for n = 0..1000</a>
%t terms = 19;
%t E2[x_] = 1 - 24*Sum[k*x^k/(1 - x^k), {k, 1, terms}];
%t E6[x_] = 1 - 504*Sum[k^5*x^k/(1 - x^k), {k, 1, terms}];
%t E2[x]^2*E6[x] + O[x]^terms // CoefficientList[#, x]& (* _Jean-François Alcover_, Feb 27 2018 *)
%Y Cf. A282018 (E_2^3), this sequence (E_2^2*E_6), A282576 (E_2*E_6^2), A282253 (E_6^3).
%K sign
%O 0,2
%A _Seiichi Manyama_, Feb 19 2017