id:A087627 - OEIS Search Results

Search: id:A087627

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Count ...n,2n,2n...

+0
1

1, 2, 2, 2, 4, 4, 3, 6, 6, 4, 8, 8, 5, 10, 10, 6, 12, 12, 7, 14, 14, 8, 16, 16, 9, 18, 18, 10, 20, 20, 11, 22, 22, 12, 24, 24, 13, 26, 26, 14, 28, 28, 15, 30, 30, 16, 32, 32, 17, 34, 34, 18, 36, 36, 19, 38, 38, 20, 40, 40, 21, 42, 42, 22, 44, 44, 23, 46, 46, 24, 48, 48, 25, 50, 50 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`a(n)=#{0<=k<=n: 3 divides k(n-k) }`
	FORMULA	`a(n)=sum{k=0..n, if (mod(k(n-k), 3)=0, 1, 0) }`
	CROSSREFS	`Sequence in context: A070705 A101909 A130872 this_sequence A096491 A106160 A007614` `Adjacent sequences: A087624 A087625 A087626 this_sequence A087628 A087629 A087630`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Sep 14 2003`

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Last modified December 7 08:40 EST 2009. Contains 170430 sequences.

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