id:A125873 - OEIS Search Results

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Prime numbers n such that cos(2pi/n) is an algebraic number of an 11-smooth degree, but not 7-smooth.

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23, 67, 89, 199, 331, 353, 397, 463, 617, 661, 727, 881, 991, 1321, 1409, 1453, 1783, 2113, 2179, 2311, 2377, 2663, 2971, 3169, 3301, 3389, 3631, 3697, 3851, 4159, 4357, 4621, 4951, 5281, 5347, 5501, 6337, 6469, 7129, 7393, 7547, 8317, 8713 (list; graph; listen)

	OFFSET	`1,1`
	MATHEMATICA	`Do[If[Take[FactorInteger[EulerPhi[2n+1]][[ -1]], 1]=={11} && PrimeQ[2n+1], Print[2n+1]], {n, 1, 10000}] (Artur Jasinski)`
	CROSSREFS	`Cf. A125866-A125878.` `Sequence in context: A125872 A104945 A141849 this_sequence A059241 A030458 A053559` `Adjacent sequences: A125870 A125871 A125872 this_sequence A125874 A125875 A125876`
	KEYWORD	`nonn`
	AUTHOR	`Artur Jasinski (grafix(AT)csl.pl), Dec 13 2006`
	EXTENSIONS	`Edited by Don Reble (djr(AT)nk.ca), Apr 24 2007`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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