id:A072438 - OEIS Search Results

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Remove prime factors of form 4*k+1.

+0
3

1, 2, 3, 4, 1, 6, 7, 8, 9, 2, 11, 12, 1, 14, 3, 16, 1, 18, 19, 4, 21, 22, 23, 24, 1, 2, 27, 28, 1, 6, 31, 32, 33, 2, 7, 36, 1, 38, 3, 8, 1, 42, 43, 44, 9, 46, 47, 48, 49, 2, 3, 4, 1, 54, 11, 56, 57, 2, 59, 12, 1, 62, 63, 64, 1, 66, 67, 4, 69, 14, 71, 72, 1, 2, 3, 76, 77, 6, 79, 16, 81, 2 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`a(n)<=n; a(a(n))=a(n).` `All factors p^m of a(n) are of the form p=2 or p=4*k+3.`
	FORMULA	`Multiplicative with a(p)=(if p==1 (mod 4) then 1 else p).`
	EXAMPLE	`a(90)=a(2335)=a(2(40+3)^2(41+1)^1=23^2*1=18.`
	CROSSREFS	`Cf. A072436, A004144, A002144, A002145.` `Sequence in context: A049073 A076388 A109680 this_sequence A132739 A060791 A116912` `Adjacent sequences: A072435 A072436 A072437 this_sequence A072439 A072440 A072441`
	KEYWORD	`nonn,mult`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 17 2002`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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