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Search: id:A152118
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| A152118 |
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Quadratic product sequence: a(n)=Product[4 + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}. |
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+0
1
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| 1, 1, 1, 5, 6, 29, 35, 169, 204, 985, 1189, 5741, 6930, 33461, 40391, 195025, 235416, 1136689, 1372105, 6625109, 7997214, 38613965, 46611179, 225058681, 271669860, 1311738121, 1583407981, 7645370045, 9228778026, 44560482149, 53789260175
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Sequence of products: Product[m + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}; m=1,2,3,4->A000045,A002530,A136211 and this one.
Apparently the same as A041011 after the initial term. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 27 2008]
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FORMULA
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a(n)=Product[4 + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}.
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MATHEMATICA
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a = Table[Product[4 + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}], {n, 0, 30}]; FullSimplify[ExpandAll[a]] Round[%]
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CROSSREFS
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A000045, A002530, A136211
Sequence in context: A115761 A127040 A041011 this_sequence A041056 A042643 A047179
Adjacent sequences: A152115 A152116 A152117 this_sequence A152119 A152120 A152121
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KEYWORD
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nonn
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AUTHOR
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Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Nov 24 2008
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