OFFSET
1,2
COMMENTS
A Collatz-Fibonacci mixture.
Conjecture: sequence diverges to infinity (a(500)=151767071).
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..10000
EXAMPLE
a(18)=43, a(19)=57, so gcd(a(18) + a(19), 4) = 4 and hence a(20) = 100/4 = 25.
MATHEMATICA
Nest[Append[#, #/GCD[#, 4] &[#[[-1]] + #[[-2]]]] &, {1, 2}, 68] (* Ivan Neretin, Jun 28 2017 *)
nxt[{a_, b_}]:={b, (a+b)/GCD[a+b, 4]}; NestList[nxt, {1, 2}, 70][[All, 1]] (* Harvey P. Dale, Jan 16 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 12 2002
STATUS
approved