id:A103775 - OEIS Search Results

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Number of ways to write n! as product of distinct square-free numbers.

+0
3

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; listen)

	OFFSET	`1,3`
	COMMENT	`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 (ppl(AT)spl.at), Jan 07 2008`
	EXAMPLE	`n=7, 7! = 1234567 = 5040 = 22223357: a(7) = #{2361014, 261042, 2614*30} = 3.`
	CROSSREFS	`Cf. A103774.` `Sequence in context: A030010 A132178 A039655 this_sequence A093057 A065334 A007814` `Adjacent sequences: A103772 A103773 A103774 this_sequence A103776 A103777 A103778`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Feb 15 2005`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

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