0,2

Leroy Quet, Home Page (listed in lieu of email address)

a(n) = Fibonacci(3^n). - Leroy Quet, March 17, 2002

The first example I know in which a(n) can be expressed as (4/5)^(1/2)*cosh(3^n*argch((5/4)^(1/2)).

a(n+1) = a(n)*A002814(n+1). - Lekraj Beedassy (blekraj(AT)yahoo.com), Jun 16 2003

a(n) = (G^(3^n) - (1 - G)^(3^n))/Sqrt[5] where G = GoldenRatio = (1 + Sqrt[5])/2 [From Artur Jasinski (grafix(AT)csl.pl), Oct 05 2008]

a(n)=(4/5)^(1/2)*cosh((3^n)*arccosh((5/4)^(1/2)). [From Artur Jasinski (grafix(AT)csl.pl), Oct 05 2008]

G = (1 + Sqrt[5])/2; Table[Expand[(G^(3^n) - (1 - G)^(3^n))/Sqrt[5]], {n, 1, 7}] [From Artur Jasinski (grafix(AT)csl.pl), Oct 05 2008]

Table[Round[(4/5)^(1/2)*Cosh[3^n*ArcCosh[((5/4)^(1/2))]]], {n, 1, 4}] [From Artur Jasinski (grafix(AT)csl.pl), Oct 05 2008]

Sequence in context: A165938 A002782 A155205 this_sequence A077747 A041012 A042459

Adjacent sequences: A045526 A045527 A045528 this_sequence A045530 A045531 A045532

nonn

Jose E. Blazek (jeblazek(AT)mate.dm.uba.ar)