A055631 - OEIS

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A055631

Sum of EulerPhi of distinct primes dividing n.

0, 1, 2, 1, 4, 3, 6, 1, 2, 5, 10, 3, 12, 7, 6, 1, 16, 3, 18, 5, 8, 11, 22, 3, 4, 13, 2, 7, 28, 7, 30, 1, 12, 17, 10, 3, 36, 19, 14, 5, 40, 9, 42, 11, 6, 23, 46, 3, 6, 5, 18, 13, 52, 3, 14, 7, 20, 29, 58, 7, 60, 31, 8, 1, 16, 13, 66, 17, 24, 11, 70, 3, 72, 37, 6, 19, 16, 15, 78, 5, 2 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	FORMULA	`a(n)=Sum[p; p divides n]=A006093(n)-A001221(n)` `Additive with a(p^e) = p-1: a(10) = a(25) = a(2)+a(5) = (2-1)+(5-1) = 5; a(28) = a(2^27) = a(2^2)+a(7) = 1+6 = 7. - Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 23 2001`
	EXAMPLE	`If n=p^w, a power of prime than a(n)=p-1; if n=2p, then a(n)=p=n/2.`
	CROSSREFS	`Cf. A001221, A006093, A053570, A053571, A055632.` `Sequence in context: A055176 A118267 A075348 * A186421 A004560 A076981` `Adjacent sequences: A055628 A055629 A055630 * A055632 A055633 A055634`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu) Jun 06 2000`

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Last modified February 14 03:03 EST 2012. Contains 205567 sequences.