A103775 - OEIS

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A103775

Number of ways to write n! as product of distinct squarefree numbers.

1, 1, 2, 0, 1, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`a(n) = 0 for n > 7;` `a(n) = A050326(A000142(n)).`
	LINKS	`Index entries for sequences related to factorial numbers.`
	FORMULA	`a(n)=[C(2n,n) mod 2]+{C[(n+1)^2,n+3] mod 2}+2[C(n^2,n+2) mod 2]+{C[(n+10)^4,n+12] mod 2}+3*{C[(n+8)^4,n+10] mod 2} - Paolo P. Lava (paoloplava(AT)gmail.com), Jan 07 2008`
	EXAMPLE	`n=7, 7! = 1234567 = 5040 = 22223357: a(7) = #{2361014, 261042, 2614*30} = 3.`
	CROSSREFS	`Cf. A103774.` `Sequence in context: A163577 A132178 A039655 * A093057 A065334 A162590` `Adjacent sequences: A103772 A103773 A103774 * A103776 A103777 A103778`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 15 2005`

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Last modified February 15 09:47 EST 2012. Contains 205762 sequences.