id:A048864 - OEIS Search Results

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Number of nonprime numbers (composites and 1) in the reduced residue system of n.

+0
9

1, 1, 1, 1, 2, 1, 3, 1, 3, 2, 6, 1, 7, 2, 4, 3, 10, 1, 11, 2, 6, 4, 14, 1, 12, 5, 10, 5, 19, 1, 20, 6, 11, 7, 15, 3, 25, 8, 14, 6, 28, 2, 29, 8, 12, 10, 32, 3, 28, 7, 19, 11, 37, 4, 26, 10, 22, 14, 42, 2, 43, 14, 20, 15, 32, 5, 48, 15, 27, 8, 51, 6, 52, 17, 21, 17, 41, 6, 57, 12, 33, 20 (list; graph; listen)

	OFFSET	`1,5`
	COMMENT	`Differs from A039776 at n = 20, 21, ...`
	FORMULA	`A000010(n) -[ A000720(n)-A(001221) ]`
	EXAMPLE	`at n=100 Phi(100) = 40 Phi(100)-[ Pi(100)-A001221(100) ]=17, thus a(100) = 17`
	CROSSREFS	`Cf. A039776, A000010, A000720, A001221.` `Sequence in context: A002616 A046073 A039776 this_sequence A003139 A111248 A100714` `Adjacent sequences: A048861 A048862 A048863 this_sequence A048865 A048866 A048867`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu)`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

AT&T Labs Research