OFFSET
3,2
COMMENTS
It appears that Fibonacci(2^(n-2)*3*m)/(2^n) is a nonnegative integer for n >= 3 and all m >= 0. The remaining factor for n >= 3 is given by A(n) := Product_{j=3..n} a(j). For n = 3 and 4 see A049660 and A253368, respectively. Thus the conjecture is that I(n; m) := Fibonacci(2^(n-2)*3*m) / ((2^n)*A(n)) is a nonnegative integer for all m >= 0. This is best possible for all m (because for m = 1 this becomes 1); special m may allow more factors. E.g., n = 3: 8 | Fibonacci(6*m), for all m >= 0, but for even m larger powers of 2 than 2^3 appear; for m = 0 any power of 2.
The factorizations of a(n) are: 1, 3^2, 7*23, 47*1103, 3167*2207, 4481*11862575248703, 127*383*769*1087*5662847*6803327*19073614849*186812208641, 885503*119809*1359361*1769526527*4698167634523379875583*74374487830388825730162393840383, ...
FORMULA
I(n; m) := F(2^(n-2)*3*m) / ((2^n)* Product_{j=3..n} a(j)) is conjectured to be a nonnegative integer for n >= 3 and all m >= 0, where F = A000045. There are no more factors > 1 for all m >= 0 because I(n, 1) = 1.
EXAMPLE
CROSSREFS
KEYWORD
nonn
AUTHOR
Wolfdieter Lang, Oct 09 2018
STATUS
approved