id:A131384 - OEIS Search Results

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Product of the digital sums of n for all the bases 1 to n (a 'digital-sum factorial').

+0
3

1, 1, 2, 2, 12, 24, 216, 192, 720, 3840, 97200, 69120, 2721600, 14515200, 130636800, 30965760, 3810240000, 3762339840, 384072192000, 445906944000, 10184771520000, 123605404876800, 12674382336000000, 2542739757465600 (list; graph; listen)

	OFFSET	`1,3`
	FORMULA	`a(n)=product{1<=p<=n, ds_p(n)} where ds_p = digital sum base p.` `a(n)=product{1<=p<=n, n-(p-1)*sum{k>0, floor(n/p^k)}}.`
	CROSSREFS	`Cf. A131383.` `Sequence in context: A092900 A122007 A137782 this_sequence A052612 A130306 A093044` `Adjacent sequences: A131381 A131382 A131383 this_sequence A131385 A131386 A131387`
	KEYWORD	`nonn`
	AUTHOR	`Hieronymus Fischer (Hieronymus.Fischer(AT)gmx.de), Jul 05 2007`

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Last modified December 2 15:58 EST 2008. Contains 150992 sequences.

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