Total number of SNIa explosions for a SSP after 10 Gyr of the birth of the SSP per unit stellar mass of the SSP predicted by Eqs. (13)–(16), assuming constant parameter B_bin and C_Ia and an IMF defined in Eq. (1), with α₁ = 1.3, α₂ = 2.3, as a function of α₃. A smaller α₃ indicates a flatter IMF/gwIMF for the massive stars, that is, a top-heavy IMF/gwIMF. Very large α₃ mean that essentially no stars above 1 M_⊙ are formed. The function is calibrated by the vertical and horizontal dashed lines indicating the canonical IMF/gwIMF slope, α₃ = 2.3, and the value n_Ia(t = 10 Gyr, ξ_canonical) = 0.0022/M_⊙ suggested by Maoz & Mannucci (2012) for the local Universe, respectively.