id:A071806 - OEIS Search Results

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Number of pairs (x,y) such that prime(x) + prime(y) = y*tau(x) + x*tau(y), 1<=x<=y<=n.

+0
1

0, 0, 0, 0, 2, 2, 2, 2, 2, 3, 3, 4, 4, 4, 4, 4, 5, 6, 7, 7, 7, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 11, 12, 12, 12, 15, 18, 18, 19, 19, 20, 20, 20, 20, 20, 20, 20, 21, 21, 22, 22, 23, 23, 23, 23, 23, 23, 24, 24, 24, 25, 26, 26, 26, 26, 28, 28, 29, 29, 29, 29, 29, 30, 31, 31, 31, 31, 31 (list; graph; listen)

	OFFSET	`1,5`
	PROGRAM	`(PARI) for(n=1, 130, print1(sum(i=1, n, sum(j=1, i, if(prime(i)+prime(j)-jnumdiv(i)-inumdiv(j), 0, 1))), ", "))`
	CROSSREFS	`Cf. A000005.` `Sequence in context: A120202 A005861 A025788 this_sequence A025781 A018119 A120502` `Adjacent sequences: A071803 A071804 A071805 this_sequence A071807 A071808 A071809`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 06 2002`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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