a(n) = (1/sqrt(5))*((sqrt(5) + 1)*((15 + 5*sqrt(5))/2)^(n-1) + (sqrt(5) - 1)*((15 - 5*sqrt(5))/2)^(n-1)).
A109106
a(n) = (1/sqrt(5))*((sqrt(5) + 1)*((15 + 5*sqrt(5))/2)^(n-1) + (sqrt(5) - 1)*((15 - 5*sqrt(5))/2)^(n-1)).
Terms
- a(0) =2a(1) =20a(2) =250a(3) =3250a(4) =42500a(5) =556250a(6) =7281250a(7) =95312500a(8) =1247656250a(9) =16332031250a(10) =213789062500
External references
- oeis: A109106