a(0)=1; a(1)=5; a(2)=11; a(n)=a(1)*a(n-1).

Terms

a(0) =1a(1) =5a(2) =11a(3) =55a(4) =275a(5) =1375a(6) =6875a(7) =34375a(8) =171875a(9) =859375a(10) =4296875a(11) =21484375a(12) =107421875a(13) =537109375a(14) =2685546875a(15) =13427734375a(16) =67138671875a(17) =335693359375