a(n) = ((2+sqrt(5))*(5+sqrt(5))^n + (2-sqrt(5))*(5-sqrt(5))^n)/2.
A162773
a(n) = ((2+sqrt(5))*(5+sqrt(5))^n + (2-sqrt(5))*(5-sqrt(5))^n)/2.
Terms
- a(0) =2a(1) =15a(2) =110a(3) =800a(4) =5800a(5) =42000a(6) =304000a(7) =2200000a(8) =15920000a(9) =115200000a(10) =833600000a(11) =6032000000a(12) =43648000000a(13) =315840000000
External references
- oeis: A162773