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 A240807 a(0)=a(1)=-1, a(2)=2; 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. 4
 -1, -1, 2, 1, 1, 3, 3, 3, 2, 4, 6, 4, 4, 5, 4, 8, 9, 6, 7, 8, 8, 8, 9, 10, 10, 9, 13, 14, 10, 12, 13, 12, 14, 15, 14, 15, 16, 16, 16, 17, 18, 18, 19, 20, 20, 20, 19, 23, 24, 20, 22, 22, 22, 25, 23, 22, 27, 27, 25, 28, 27, 27, 29, 29, 29, 29, 31, 31, 31, 32, 32, 32, 33, 34, 34, 35, 36, 36, 36, 37, 38, 38, 39, 40, 40, 40, 40, 39, 43, 44, 40, 42, 42, 42 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 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 N. J. A. Sloane, Table of n, a(n) for n = 0..20000 MAPLE a:=proc(n) option remember; if n = 0 then  -1 elif n = 1 then -1 elif n = 2 then 2 else     if (a(n-1) <= n-1) and (a(n-2) <= n-2) then     a(n-1-a(n-1))+a(n-2-a(n-2));     else lprint("died with n =", n); return (-1);     fi; fi; end; [seq(a(n), n=0..100)]; PROG (Haskell) a240807 n = a240807_list !! n a240807_list = -1 : -1 : 2 : zipWith (+) xs (tail xs)    where xs = map a240807 \$ zipWith (-) [1..] \$ tail a240807_list -- Reinhard Zumkeller, Apr 17 2014 CROSSREFS A006949 and A240808 have the same recurrence but different initial conditions. Sequence in context: A308028 A320902 A189913 * A334347 A283672 A053268 Adjacent sequences:  A240804 A240805 A240806 * A240808 A240809 A240810 KEYWORD sign AUTHOR N. J. A. Sloane, Apr 15 2014 STATUS approved

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Last modified May 9 13:42 EDT 2021. Contains 343742 sequences. (Running on oeis4.)