3339294domain: NAppears in sequencesa(6n+k) = 3a(6n+k-1)-3a(6n+k-2)+2a(6n+k-3), k = 0, 1, 3, 4, 5; a(6n+2) = 3a(6n+1)-3a(6n). a(0) = a(1) = 0, a(2) = 1.at n=25A132658a(n) = p^3*(p-1), where p = prime(n).at n=13A138403