Subject: Hofstadter Sequence (G"odel Escher Bach)

  1,1,2,3,3,4,5,5,6,6,6,8,8,8,10,9,10,11,11,12,12,12,12,
    16,14,14,16,16,16,16,20,17,17,20,21,19,20,...

  Recursion: a(1)=a(2)=1,
	     a(n) = a(n-a(n-1)) + a(n-a(n-2))  for n>2

  Asymptotic: a(n) = n/2 + o(n)

HOS: Hofstadter Sequence:
HOS  a(1)=a(2)=1, a(n) = a(n-a(n-1)) + a(n-a(n-2))
HOS- E31, R. K. Guy, Unsolved problems in number theory, 1981, 1 Ref
HOS- S. M. Tanny, A well-behaved cousin of the Hofstadter sequence,
HOS    Disc. Math. 105 (1992) 227-239
HOS- Conway's Challenge Sequence, AMM 98 (1991) 5-20, 99 (1992) 563-564
HOS- Conway's Challange, AMM 100 (1993) 396-397
HOS- -Tal Kubo    kubo@math.harvard.edu  or  kubo@zariski.harvard.edu
HOS   A draft of the article is available (in AMSLaTeX format).  Interested
HOS   parties should contact me by e-mail. <- Conway's Challenge Sequence