

A240808


a(0)=2, a(1)=1, a(2)=0; thereafter a(n) = a(n1a(n1))+a(n2a(n2)) unless a(n1) <= n1 or a(n2) <= n2 in which case the sequence terminates.


8



2, 1, 0, 2, 1, 3, 2, 1, 3, 5, 4, 3, 5, 4, 6, 8, 4, 6, 8, 7, 9, 8, 7, 12, 11, 7, 12, 14, 10, 12, 14, 10, 12, 17, 13, 12, 20, 16, 12, 20, 19, 15, 20, 19, 18, 23, 19, 21, 26, 19, 21, 26, 19, 24, 29, 19, 27, 32, 19, 27, 32, 22, 30, 32, 22, 30, 32, 25, 33, 32, 28, 36, 32, 31, 39, 32, 31, 42, 35, 31, 45, 38, 31, 45, 38, 31, 48, 41, 31, 51, 44, 31, 51, 47, 34
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OFFSET

0,1


COMMENTS

a(A241218(n)) = n and a(m) <> n for m < A241218(n).  Reinhard Zumkeller, Apr 17 2014


REFERENCES

Higham, Jeff and Tanny, Stephen, A tamely chaotic metaFibonacci sequence. Twentythird Manitoba Conference on Numerical Mathematics and Computing (Winnipeg, MB, 1993). Congr. Numer. 99 (1994), 6794. [Contains a detailed analysis of this sequence]


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..20000
Rémy Sigrist, Colored scatterplot of a(n) for n = 0..20000 (where the color is function of n mod 3)
Index entries for Hofstadtertype sequences


MAPLE

a:=proc(n) option remember; global k;
if n = 0 then 2
elif n = 1 then 1
elif n = 2 then 0
else
if (a(n1) <= n1) and (a(n2) <= n2) then
a(n1a(n1))+a(n2a(n2));
else lprint("died with n =", n); return (1);
fi;
fi; end;
[seq(a(n), n=0..100)];


PROG

(Haskell)
a240808 n = a240808_list !! n
a240808_list = 2 : 1 : 0 : zipWith (+) xs (tail xs)
where xs = map a240808 $ zipWith () [1..] $ tail a240808_list
 Reinhard Zumkeller, Apr 17 2014


CROSSREFS

A006949 and A240807 have the same recurrence but different initial conditions.
Trisections: A244780..A244782.
Sequence in context: A153247 A071432 A194508 * A263142 A025253 A281228
Adjacent sequences: A240805 A240806 A240807 * A240809 A240810 A240811


KEYWORD

nonn,look


AUTHOR

N. J. A. Sloane, Apr 15 2014


STATUS

approved



