A057951 - OEIS

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A057951

Number of prime factors of 10^n - 1 (counted with multiplicity).

2, 3, 4, 4, 4, 7, 4, 6, 6, 6, 4, 9, 5, 6, 8, 8, 4, 11, 3, 9, 9, 9, 3, 12, 7, 8, 9, 10, 7, 15, 5, 13, 8, 8, 9, 14, 5, 5, 8, 13, 6, 17, 6, 13, 12, 8, 4, 15, 6, 12, 10, 11, 6, 16, 10, 14, 8, 10, 4, 22, 9, 7, 16, 17, 9, 17, 5, 12, 8, 14, 4, 20, 5, 9, 14, 8, 10, 18 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`a(n) = Omega(10^n -1) = Omega(R_n) + 2 = A046053(n) + 2 {where Omega(n)=A001222(n) and R_n=(10^n -1)/9=A002275(n)}. - Lekraj Beedassy, Jun 09 2006`
	LINKS	`T. D. Noe, Table of n, a(n) for n = 1..500` `S. S. Wagstaff, Jr., Main Tables from the Cunningham Project.` `S. S. Wagstaff, Jr., The Cunningham Project`
	FORMULA	`Mobius transform of A085035 - T. D. Noe, Jun 19 2003`
	MATHEMATICA	`PrimeOmega[10^Range[70]-1] (* Jayanta Basu, May 29 2013 *)`
	CROSSREFS	`Cf. A057952-A057958, A046051.` `Cf. A085035.` `Sequence in context: A206925 A114212 A108355 * A076410 A211509 A058277` `Adjacent sequences: A057948 A057949 A057950 * A057952 A057953 A057954`
	KEYWORD	`nonn`
	AUTHOR	`Patrick De Geest, Nov 15 2000.`
	STATUS	`approved`

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Last modified September 10 18:27 EDT 2015. Contains 261502 sequences.