id:A073256 - OEIS Search Results

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EulerPhi of n-th composite number.

+0
2

2, 2, 4, 6, 4, 4, 6, 8, 8, 6, 8, 12, 10, 8, 20, 12, 18, 12, 8, 16, 20, 16, 24, 12, 18, 24, 16, 12, 20, 24, 22, 16, 42, 20, 32, 24, 18, 40, 24, 36, 28, 16, 30, 36, 32, 48, 20, 32, 44, 24, 24, 36, 40, 36, 60, 24, 32, 54, 40, 24, 64, 42, 56, 40, 24, 72, 44, 60, 46, 72, 32, 42, 60 (list; graph; listen)

	OFFSET	`1,1`
	FORMULA	`a(n)=A000010[A002808(n)]`
	EXAMPLE	`100th composite is 133, phi[133]=108=a(100).`
	MATHEMATICA	`c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Table[EulerPhi[c[w], {w, 1, 128}]`
	CROSSREFS	`Cf. A000010, A002808, A035004, A073255.` `Sequence in context: A127718 A115068 A051495 this_sequence A166362 A050469 A085730` `Adjacent sequences: A073253 A073254 A073255 this_sequence A073257 A073258 A073259`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Jul 22 2002`

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Last modified December 21 10:15 EST 2009. Contains 171081 sequences.

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