id:A007875 - OEIS Search Results

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Number of ways of writing n as pq, with p<=q, (p,q)=1.

+0
6

1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 4, 1, 1, 2, 2, 2, 2, 1, 2, 2, 2, 1, 4, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 4, 1, 2, 2, 1, 2, 4, 1, 2, 2, 4, 1, 2, 1, 2, 2, 2, 2, 4, 1, 2, 1, 2, 1, 4, 2, 2, 2, 2, 1, 4 (list; graph; listen)

	OFFSET	`1,6`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..1000`
	FORMULA	`a(n)= (1/2) *Sum_{ d divides n } abs(mu(d))=2^(A001221(n)-1)=A034444(n)/2, n > 1. - Vladeta Jovovic (vladeta(AT)eunet.rs), Jan 25 2002`
	CROSSREFS	`Sequence in context: A001221 A064372 A096825 this_sequence A050320 A121382 A051265` `Adjacent sequences: A007872 A007873 A007874 this_sequence A007876 A007877 A007878`
	KEYWORD	`nonn,nice,easy`
	AUTHOR	`Victor Ufnarovski`

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.

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