A055654 - OEIS

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A055654

Difference between n and the result of "Phi-summation" over unitary divisors of n.

0, 0, 0, 1, 0, 0, 0, 3, 2, 0, 0, 3, 0, 0, 0, 7, 0, 4, 0, 5, 0, 0, 0, 9, 4, 0, 8, 7, 0, 0, 0, 15, 0, 0, 0, 15, 0, 0, 0, 15, 0, 0, 0, 11, 10, 0, 0, 21, 6, 8, 0, 13, 0, 16, 0, 21, 0, 0, 0, 15, 0, 0, 14, 31, 0, 0, 0, 17, 0, 0, 0, 37, 0, 0, 12, 19, 0, 0, 0, 35, 26, 0, 0, 21, 0, 0, 0, 33, 0, 20, 0, 23 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,8`
	FORMULA	`a(n)=n-Sum[Phi[u]], where GCD[u, n/u] = 1, i.e. u is unitary divisor of n.`
	EXAMPLE	`Squarefree numbers are roots of a(n)=0 equation, while Min n for which a(n)=k is k^2. See also A000188, A008833.`
	CROSSREFS	`Cf. A000188, A008833, A055653, A053570, A053571, A055631, A055632.` `Sequence in context: A206825 A133949 A139808 * A170849 A062787 A131370` `Adjacent sequences: A055651 A055652 A055653 * A055655 A055656 A055657`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Jun 07 2000`

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Last modified February 17 21:13 EST 2012. Contains 206085 sequences.