id:A125876 - OEIS Search Results

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Prime numbers n such that cos(2pi/n) is an algebraic number of a 13-smooth degree, but not 11-smooth.

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53, 79, 131, 157, 313, 521, 547, 677, 859, 911, 937, 1093, 1171, 1249, 1301, 1873, 1951, 2003, 2029, 2081, 2341, 2549, 2731, 2861, 3121, 3251, 3329, 3433, 3511, 3719, 3823, 4057, 4733, 4993, 5851, 6007, 6553, 6761, 7151, 7489, 7723, 8009 (list; graph; listen)

	OFFSET	`1,1`
	MATHEMATICA	`Do[If[Take[FactorInteger[EulerPhi[2n+1]][[ -1]], 1]=={13} && PrimeQ[2n+1], Print[2n+1]], {n, 1, 10000}] (Artur Jasinski)`
	CROSSREFS	`Cf. A125866-A125878.` `Sequence in context: A129257 A125875 A059245 this_sequence A136065 A001836 A118149` `Adjacent sequences: A125873 A125874 A125875 this_sequence A125877 A125878 A125879`
	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 September 6 09:40 EDT 2008. Contains 143480 sequences.

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