A386818 Coefficients in q-expansion of E_2^2 * E_6^2, where E_2 and E_6 are respectively the Eisenstein series A006352 and A013973.

1, -1056, 269568, 5490816, -301315008, -6705063360, 41022885888, 1997915006208, 25923296790720, 210257663162208, 1273067731422720, 6245405396604288, 26057761857270528, 95466552284986176, 314217210391363584, 945049912933328640, 2631525397984618944, 6854687219510589888

Offset: 0

Author

Vaclav Kotesovec, Aug 03 2025

Keywords

• sign

Crossrefs

Cf. A006352, A013973, A386787.

Programs

Mathematica

terms = 20;
E2[x_] = 1 - 24*Sum[k*x^k/(1 - x^k), {k, 1, terms}];
E6[x_] = 1 - 504*Sum[k^5*x^k/(1 - x^k), {k, 1, terms}];
CoefficientList[Series[E2[x]^2*E6[x]^2, {x, 0, 20}], x]