OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..7
FORMULA
a(n) = (1/(10*sqrt(2)))*((1 + sqrt(2))^(3^n) - (1 - sqrt(2))^(3^n)).
a(n+1) = 200*a(n)^3 - 3*a(n), a(1) = 1.
a(n) = A000129(3^n)/5 . - R. J. Mathar, Jan 18 2021
MATHEMATICA
Table[Simplify[Expand[(1/(10Sqrt[2]))((1+Sqrt[2])^(3^n) + (1-Sqrt[2])^(3^n))]], {n, 5}]
Fibonacci[3^Range[6], 2]/5 (* G. C. Greubel, Mar 25 2022 *)
PROG
(Magma) [Evaluate(DicksonSecond(3^n -1, -1), 2)/5: n in [1..6]]; // G. C. Greubel, Mar 25 2022
(Sage) [lucas_number1(3^n, 2, -1)/5 for n in (1..6)] # G. C. Greubel, Mar 25 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Oct 10 2008
EXTENSIONS
Offset corrected by R. J. Mathar, Jan 18 2021
STATUS
approved