267331domain: NAppears in sequencesa(1)=1, a(n) = n*15^(n-1) + a(n-1).at n=4A0149301+2n+3n^2+4n^3+5n^4.at n=15A056579Zsigmondy numbers for a = 3, b = 2: Zs(n, 3, 2) is the greatest divisor of 3^n - 2^n (A001047) that is relatively prime to 3^m - 2^m for all positive integers m < n.at n=20A109325