id:A157684 - OEIS Search Results

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a(n)=#{1<=k<=n : [K(k),K(k+1)]=[1,2]} where K=A000002

+0
4

1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, 9, 9, 10, 10, 10, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20, 20, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 24, 24, 25, 25, 25, 26, 26, 26, 27 (list; graph; listen)

	OFFSET	`1,5`
	COMMENT	`Presumably a(n)=n/3+o(n)`
	PROGRAM	`(PARI) a(n)=sum(k=1, n, if(abs(A000002(k)-1)+abs(A000002(k+1)-2), 0, 1))`
	CROSSREFS	`Cf. A157685, A157686, A157687` `Sequence in context: A087831 A058032 A056155 this_sequence A026099 A049727 A060802` `Adjacent sequences: A157681 A157682 A157683 this_sequence A157685 A157686 A157687`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 04 2009`

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Last modified December 4 08:07 EST 2009. Contains 170310 sequences.

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