id:A099774 - OEIS Search Results

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Number of divisors of 2n-1.

+0
7

1, 2, 2, 2, 3, 2, 2, 4, 2, 2, 4, 2, 3, 4, 2, 2, 4, 4, 2, 4, 2, 2, 6, 2, 3, 4, 2, 4, 4, 2, 2, 6, 4, 2, 4, 2, 2, 6, 4, 2, 5, 2, 4, 4, 2, 4, 4, 4, 2, 6, 2, 2, 8, 2, 2, 4, 2, 4, 6, 4, 3, 4, 4, 2, 4, 2, 4, 8, 2, 2, 4, 4, 4, 6, 2, 2, 6, 4, 2, 4, 4, 2, 8, 2, 3, 6, 2, 6, 4, 2, 2, 4, 4, 4, 8, 2, 2, 8, 2, 2, 4, 4, 4, 6, 4 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`G.f.: Sum_{k>0} x^k/(1-x^(2k-1)) . - Michael Somos Sep 02 2006`
	EXAMPLE	`a(5)=3 because the divisors of 9 are: 1, 3, and 9.`
	MAPLE	`with(numtheory): seq(tau(2*n-1), n=1..120);`
	PROGRAM	`(PARI) {a(n)=if(n<1, 0, numdiv(2n-1))} / Michael Somos Sep 03 2006 */`
	CROSSREFS	`Bisection of A000005.` `Cf. A000005, A099777.` `Sequence in context: A138789 A116504 A104011 this_sequence A048288 A050677 A058013` `Adjacent sequences: A099771 A099772 A099773 this_sequence A099775 A099776 A099777`
	KEYWORD	`nonn,easy`
	AUTHOR	`njas, Nov 19 2004`
	EXTENSIONS	`More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 03 2004`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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