A087777 - OEIS

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A087777

a(1) = ... = a(4) = 1; a(n)=a(n-a(n-2))+a(n-a(n-4)).

1, 1, 1, 1, 2, 4, 6, 7, 7, 5, 3, 8, 9, 11, 12, 9, 9, 13, 11, 9, 13, 16, 13, 19, 16, 11, 14, 16, 21, 22, 14, 14, 19, 17, 22, 27, 25, 16, 20, 28, 22, 22, 26, 25, 24, 32, 26, 22, 29, 29, 32, 35, 32, 27, 26, 34, 30, 33, 40, 25, 27, 46, 40, 33, 32, 28, 36, 50, 44, 31, 36, 38, 46, 53, 41, 29, 41 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,5`
	COMMENTS	`It is not known if this sequence is defined for all positive n. Balamohan et al. comment that it shows "inscrutably wild behavior".`
	LINKS	`N. J. A. Sloane, Table of n, a(n) for n = 1..10000` `B. Balamohan, A. Kuznetsov and S. Tanny, On the behavior of a variant of Hofstadter's Q-sequence, J. Integer Sequences, Vol. 10 (2007), #07.7.1.` `Index entries for Hofstadter-type sequences`
	MAPLE	`a := proc(n) option remember; if n<=4 then 1 else if n > a(n-2) and n > a(n-4) then RETURN(a(n-a(n-2))+a(n-a(n-4))); else ERROR(" died at n= ", n); fi; fi; end;`
	CROSSREFS	`Cf. A005185, A063882, A046700.` `Sequence in context: A114431 A167689 A058184 * A030118 A023835 A174416` `Adjacent sequences: A087774 A087775 A087776 * A087778 A087779 A087780`
	KEYWORD	`nonn`
	AUTHOR	`Roger L. Bagula, Oct 05 2003`
	EXTENSIONS	`Edited by N. J. A. Sloane, Nov 06 2007`
	STATUS	`approved`

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Last modified May 24 05:21 EDT 2013. Contains 225616 sequences.