127639domain: NAppears in sequencesZsigmondy numbers for a = 7, b = 3: Zs(n, 7, 3) is the greatest divisor of 7^n - 3^n that is relatively prime to 7^m - 3^m for all positive integers m < n.at n=8A109348Expansion of e.g.f.: 1/(3 - exp(x) - cosh(x)).at n=7A352327