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A152119 A product sequence: a(n)=Product[5 + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}]. +0
2
1, 1, 1, 6, 7, 41, 48, 281, 329, 1926, 2255, 13201, 15456, 90481, 105937, 620166, 726103, 4250681, 4976784, 29134601, 34111385, 199691526, 233802911, 1368706081, 1602508992, 9381251041, 10983760033, 64300051206, 75283811239 (list; graph; listen)
OFFSET

0,4

FORMULA

a(n)=Product[5 + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}].

MATHEMATICA

a = Table[Product[5 + 4*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}], {n, 0, 30}]; Round[%] FullSimplify[ExpandAll[a]]

CROSSREFS

Sequence in context: A025626 A027021 A013627 this_sequence A041080 A042091 A047181

Adjacent sequences: A152116 A152117 A152118 this_sequence A152120 A152121 A152122

KEYWORD

nonn

AUTHOR

Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Nov 24 2008

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Last modified December 1 19:22 EST 2009. Contains 167811 sequences.


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