A244483 a(0)=3, a(1)=1, a(2)=0; thereafter a(n) = a(n-1-a(n-1))+a(n-2-a(n-2)) unless a(n-1) <= n-1 or a(n-2) <= n-2 in which case the sequence terminates.

3, 1, 0, 3, 3, 4, 2, 4, 6, 3, 2, 8, 9, 6, 7, 8, 8, 10, 10, 10, 9, 11, 10, 11, 18, 11, 9, 17, 12, 10, 18, 19, 18, 16, 17, 20, 18, 18, 20, 20, 20, 19, 19, 21, 21, 21, 29, 28, 20, 22, 29, 28, 22, 29, 36, 28, 27, 27, 28, 36, 29, 30, 38, 37, 27, 27, 38, 32, 32, 38, 37, 35, 34, 38, 40, 37, 37, 40, 38, 38, 39

Offset: 0

Author

N. J. A. Sloane, Jul 03 2014

Keywords

• nonn

References

• Higham, Jeff and Tanny, Stephen, A tamely chaotic meta-Fibonacci sequence. Twenty-third Manitoba Conference on Numerical Mathematics and Computing (Winnipeg, MB, 1993). Congr. Numer. 99 (1994), 67-94.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
• Index entries for Hofstadter-type sequences

Crossrefs

See A006949 for overview of sequences produced by this recurrence and various initial conditions.

Programs

Haskell

a244483 n = a244483_list !! n
a244483_list = 3 : 1 : 0 : zipWith (+) xs (tail xs)
   where xs = map a244483 $ zipWith (-) [1..] $ tail a244483_list
-- Reinhard Zumkeller, Jul 07 2014

Maple

f := proc(n) option remember;
    if n=0 then 3
    elif n=1 then 1
    elif n=2 then 0
    else
    f(n-1-f(n-1))+f(n-2-f(n-2));
    fi;
end proc;
[seq(f(n),n=0..80)];