A046798 - OEIS

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A046798

Number of divisors of 2^n+1.

2, 2, 2, 3, 2, 4, 4, 4, 2, 8, 6, 4, 4, 4, 8, 12, 2, 4, 16, 4, 4, 12, 8, 4, 8, 16, 16, 20, 4, 8, 48, 4, 4, 24, 16, 32, 16, 8, 16, 12, 4, 8, 64, 4, 8, 64, 32, 8, 8, 8, 64, 48, 8, 8, 64, 48, 8, 24, 8, 16, 16, 4, 32, 64, 4, 64, 64, 8, 12, 24, 96, 8, 32, 8, 32, 96, 16, 64, 768, 4, 8, 192, 32, 64 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,1`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..500 (using data from A001269)`
	EXAMPLE	`a[ 7 ]=129 with 4 divisors`
	MATHEMATICA	`A046798[n_IntegerQ]:=DivisorSigma[0, 1+2^n]; [From Enrique Perez Herrero (psychgeometry(AT)gmail.com), Nov 09 2010]`
	CROSSREFS	`Cf. A000051.` `Sequence in context: A035433 A029199 A121611 * A157231 A104239 A058614` `Adjacent sequences: A046795 A046796 A046797 * A046799 A046800 A046801`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu)`

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Last modified February 15 21:27 EST 2012. Contains 205859 sequences.