A067017 Start with a(0)=1, a(1)=4, a(2)=3, a(3)=2; for n>=3, a(n+1) = mex_i (a(i)+a(n-i)), where mex means smallest nonnegative missing number.

1, 4, 3, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0, 0, 0, 5, 1, 1, 1, 1, 1, 6, 2, 2, 0, 0, 0

Offset

0,2

References

R. K. Guy, Unsolved Problems in Number Theory, E27.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Prog

(Haskell)
import Data.List ((\\))
a067017 n = a067017_list !! n
a067017_list =  [1, 4, 3, 2] ++ f [2, 3, 4, 1] where
  f xs = mexi : f (mexi : xs) where
    mexi = head $ [0..] \\ zipWith (+) xs (reverse xs)
-- Reinhard Zumkeller, May 05 2012

Crossrefs

Cf. A067016, A067018.

Sequence in context: A143543 A176863 A349989 * A258692 A067018 A200233

Adjacent sequences: A067014 A067015 A067016 * A067018 A067019 A067020

Keyword

nonn,easy

Author

N. J. A. Sloane, Feb 17 2002

Extensions

More terms from John W. Layman, Feb 20 2002

Status

approved