id:A081240 - OEIS Search Results

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#{(i,j): mu(i)*mu(j) = 1, 1<=i,j<=n}, where mu=A008683 (Moebius function).

+0
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1, 2, 5, 5, 10, 13, 20, 20, 20, 25, 34, 34, 45, 52, 61, 61, 74, 74, 89, 89, 100, 113, 130, 130, 130, 145, 145, 145, 164, 185, 208, 208, 225, 244, 265, 265, 290, 313, 338, 338, 365, 394, 425, 425, 425, 452, 485, 485, 485, 485, 514, 514, 549, 549, 580, 580, 613 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`A081238(n) + A081239(n) + a(n) = n^2;` `a(n) = a(n-1) iff mu(n) = 0.`
	EXAMPLE	`n mu(n) ... n: 1 2 3 4 5 6 7 8` `- ------ .... \|---------------->` `1 .. +1 ..... \| + - - 0 - + - 0` `2 .. -1 ..... \| - + + 0 + - + 0` `3 .. -1 ..... \| - + + 0 + - + 0` `4 ... 0 ..... \| 0 0 0 0 0 0 0 0` `5 .. -1 ..... \| - + + 0 + - + 0 a(8)=20, as there are` `6 .. +1 ..... \| + - - 0 - + - 0 20 '+1's in the 8x8-square` `7 .. -1 ..... \| - + + 0 + - + 0 (represented as '+')` `8 ... 0 ..... \| 0 0 0 0 0 0 0 0.`
	CROSSREFS	`Cf. A070548.` `Sequence in context: A050175 A059797 A034387 this_sequence A132295 A086651 A074495` `Adjacent sequences: A081237 A081238 A081239 this_sequence A081241 A081242 A081243`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 11 2003`

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Last modified September 8 13:03 EDT 2008. Contains 143486 sequences.

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