id:A085343 - OEIS Search Results

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Number of primes between sigma[n] and phi[n].

+0
2

0, 2, 1, 3, 1, 4, 1, 4, 3, 5, 1, 7, 1, 6, 5, 7, 1, 9, 1, 9, 6, 7, 1, 13, 3, 8, 5, 11, 1, 16, 1, 12, 7, 10, 6, 19, 1, 10, 7, 18, 1, 19, 1, 15, 12, 12, 1, 24, 3, 16, 9, 16, 1, 23, 8, 21, 11, 15, 1, 33, 1, 14, 16, 20, 8, 26, 1, 19, 10, 25, 1, 35, 1, 19, 18, 23, 7, 30, 1, 31, 14, 18, 1, 39, 10, 19 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n)=Pi[sigma(n)]-Pi[phi(n)]=-A000720[A000203(n)]-A000720[A000010(n)]`
	EXAMPLE	`n=12: sigma(12)=28, phi(n)=4, Pi(28)-Pi(4)=9-2=7`
	CROSSREFS	`Cf. A000720, A000010, A000203, A070803, A070804, A085341-A085347.` `Sequence in context: A029234 A102613 A097019 this_sequence A049077 A077609 A077610` `Adjacent sequences: A085340 A085341 A085342 this_sequence A085344 A085345 A085346`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Jul 10 2003`

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Last modified December 8 08:31 EST 2009. Contains 170430 sequences.

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