381405156481domain: NAppears in sequencesa(n) = (5^n - 3^n)/2.at n=17A005059Zsigmondy numbers for a = 5, b = 3: Zs(n, 5, 3) is the greatest divisor of 5^n - 3^n (A005058) that is relatively prime to 5^m - 3^m for all positive integers m < n.at n=16A109347For n>1, a(n) = 2*a(n-1) + 15*a(n-2); a(0)=1, a(1)=1.at n=17A120612