id:A133801 - OEIS Search Results

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Number of distinct prime divisors of 3^n - 1.

+0
1

1, 1, 2, 2, 2, 3, 2, 3, 3, 3, 3, 5, 2, 3, 4, 5, 3, 6, 3, 5, 4, 5, 3, 7, 4, 3, 6, 6, 4, 8, 4, 6, 5, 6, 5, 9, 3, 5, 6, 7, 4, 8, 3, 8, 8, 4, 5, 12, 7, 7, 6, 6, 4, 11, 6, 9, 7, 7, 3, 12, 3, 6, 6, 7, 6, 10, 4, 9, 6, 8, 2, 12, 5, 6, 9, 8, 7, 12, 4, 11, 9, 6, 5, 14, 6, 4, 8, 12, 4, 16, 5, 7, 7, 8, 6, 15, 4, 10, 8 (list; graph; listen)

	OFFSET	`1,3`
	REFERENCES	`Eric Weisstein's World of Mathematics, "Prime Factor", http://mathworld.wolfram.com/PrimeFactor.html`
	FORMULA	`a(n) = omega(3^n - 1) = A001221(3^n - 1)`
	EXAMPLE	`a(4) = omega(3^4 - 1) = omega(80) = omega(2^4 * 5) = 2.`
	PROGRAM	`(PARI) for(n = 1, 100, print1(omega(3^n - 1), ", "))`
	CROSSREFS	`Cf. A113913.` `Adjacent sequences: A133798 A133799 A133800 this_sequence A133802 A133803 A133804` `Sequence in context: A076869 A104307 A128330 this_sequence A112310 A137734 A078705`
	KEYWORD	`nonn`
	AUTHOR	`Ryan Propper (rpropper(AT)cs.stanford.edu), Jan 06 2008`

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Last modified October 7 14:39 EDT 2008. Contains 144666 sequences.

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