a(n) = ((4+sqrt(5))*(5+sqrt(5))^n + (4-sqrt(5))*(5-sqrt(5))^n)/2.
A163072
a(n) = ((4+sqrt(5))*(5+sqrt(5))^n + (4-sqrt(5))*(5-sqrt(5))^n)/2.
Terms
- a(0) =4a(1) =25a(2) =170a(3) =1200a(4) =8600a(5) =62000a(6) =448000a(7) =3240000a(8) =23440000a(9) =169600000a(10) =1227200000a(11) =8880000000a(12) =64256000000a(13) =464960000000
External references
- oeis: A163072