New non-linear equations and modular form expansion for double-elliptic Seiberg–Witten prepotential G. Aminov, A. Mironov and A. Morozov Eur. Phys. J. C, 76 8 (2016) 433 Published online: 02 August 2016 DOI: 10.1140/epjc/s10052-016-4267-6