A340371 - OEIS

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A340371

a(n) = 1 if the odd part of n is noncomposite, 0 otherwise.

1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1`
	COMMENTS	`a(n) = 1 if n is of the form 2^i * p^j, for some odd prime p, with i >= 0, 0 <= j <= 1, and 0 otherwise.`
	LINKS	`Antti Karttunen, Table of n, a(n) for n = 1..65537` `Index entries for characteristic functions`
	FORMULA	`a(n) = A080339(A000265(n)).` `For n > 1, a(n) = abs(A304438(n)).`
	PROG	`(PARI) A340371(n) = (2>bigomega(n>>valuation(n, 2)));`
	CROSSREFS	`Cf. A000265, A080339.` `Characteristic function of A093641.` `After the initial term, the absolute values of A304438.` `Cf. also A340370, A340373.` `Differs from A340374 for the first time at n=561, where a(561) = 0.` `Sequence in context: A334460 A071023 A166280 * A340374 A070887 A209635` `Adjacent sequences: A340368 A340369 A340370 * A340372 A340373 A340374`
	KEYWORD	`nonn`
	AUTHOR	`Antti Karttunen, Jan 06 2021`
	STATUS	`approved`

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Last modified March 29 09:20 EDT 2023. Contains 361598 sequences. (Running on oeis4.)