a(n) = 5*a(n-1) + 45*a(n-3) - 225*a(n-4), a(0)=0, a(1)=4, a(2)=24, a(3)=60, a(4)=480.

A112611

a(n) = 5*a(n-1) + 45*a(n-3) - 225*a(n-4), a(0)=0, a(1)=4, a(2)=24, a(3)=60, a(4)=480.

Terms

    a(0) =0a(1) =4a(2) =24a(3) =60a(4) =480a(5) =2580a(6) =10200a(7) =59100a(8) =303600a(9) =1396500a(10) =7347000a(11) =37099500a(12) =180030000a(13) =916552500a(14) =4599165000a(15) =22749787500a(16) =114487050000a(17) =573173362500

External references