A046801 - OEIS

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A046801

Number of divisors of 2^n-1.

0, 1, 2, 2, 4, 2, 6, 2, 8, 4, 8, 4, 24, 2, 8, 8, 16, 2, 32, 2, 48, 12, 16, 4, 96, 8, 8, 8, 64, 8, 96, 2, 32, 16, 8, 16, 512, 4, 8, 16, 192, 4, 144, 8, 128, 64, 16, 8, 768, 4, 128, 32, 128, 8, 160, 64, 256, 16, 64, 4, 4608, 2, 8, 96, 128, 8, 384, 4, 128, 16, 512, 8, 8192, 8, 32, 128 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	LINKS	`T. D. Noe, Table of n, a(n) for n=0..500 (using data from A001265)`
	FORMULA	`a[ n ] = DivisorSigma [ 0, 2^n -1 ] ]`
	EXAMPLE	`a[ 120 ]=73728 since 2^120-1 has that many divisors.`
	CROSSREFS	`Cf. A000225.` `Sequence in context: A071364 A067824 A107067 * A137502 A143112 A167272` `Adjacent sequences: A046798 A046799 A046800 * A046802 A046803 A046804`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu)`
	EXTENSIONS	`Typo in example fixed by Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 15 2010`

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Last modified February 14 11:27 EST 2012. Contains 205623 sequences.