id:A008328 - OEIS Search Results

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Number of divisors of p-1, p prime.

+0
3

1, 2, 3, 4, 4, 6, 5, 6, 4, 6, 8, 9, 8, 8, 4, 6, 4, 12, 8, 8, 12, 8, 4, 8, 12, 9, 8, 4, 12, 10, 12, 8, 8, 8, 6, 12, 12, 10, 4, 6, 4, 18, 8, 14, 9, 12, 16, 8, 4, 12, 8, 8, 20, 8, 9, 4, 6, 16, 12, 16, 8, 6, 12, 8, 16, 6, 16, 20, 4, 12, 12, 4, 8, 12, 16, 4, 6, 18, 15, 16, 8, 24, 8 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also the number of irreducible factors of Phi(p,x)-1, for cyclotomic polynomial Phi(p,x) and prime p. The formula is Phi(p,x)-1 = x Prod {n>1, n\|p-1} Phi(n,x). - T. D. Noe (noe(AT)sspectra.com), Oct 17 2003`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..10000` `Eric Weisstein's World of Mathematics, Cyclotomic Polynomial`
	MAPLE	`for i from 1 to 500 do if isprime(i) then print(tau(i-1)); fi; od;`
	CROSSREFS	`Sequence in context: A036804 A008329 A064558 this_sequence A091860 A071323 A071324` `Adjacent sequences: A008325 A008326 A008327 this_sequence A008329 A008330 A008331`
	KEYWORD	`nonn`
	AUTHOR	`njas`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

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