id:A152191 - OEIS Search Results

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a(n)=Product[(1 + 4*Cos[k*Pi/n]^2)*(1 - 4*Sin[k*Pi/n]^2), {k, 1, Floor[(n - 1)/2]}].

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1, 1, 1, -4, -3, 5, 0, 13, 21, -68, -55, 89, 0, 233, 377, -1220, -987, 1597, 0, 4181, 6765, -21892, -17711, 28657, 0, 75025, 121393, -392836, -317811, 514229, 0 (list; graph; listen)

	OFFSET	`0,4`
	MATHEMATICA	`f[n_] = Product[(1 + 4Cos[kPi/n]^2)(1 - 4Sin[k*Pi/n]^2), {k, 1, Floor[(n - 1)/2]}]; Table[N[f[n]], {n, 0, 30}]; Round[%]`
	CROSSREFS	`Sequence in context: A060374 A074296 A085961 this_sequence A029934 A011397 A081665` `Adjacent sequences: A152188 A152189 A152190 this_sequence A152192 A152193 A152194`
	KEYWORD	`sign`
	AUTHOR	`Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Nov 28 2008`

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Last modified March 20 09:10 EDT 2010. Contains 173642 sequences.

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