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A273413
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Decimal expansion of Product_{k>=0} (1 + 1/2^(2k))^(-1/2).
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2
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6, 0, 7, 2, 5, 2, 9, 3, 5, 0, 0, 8, 8, 8, 1, 2, 5, 6, 1, 6, 9, 4, 4, 6, 7, 5, 2, 5, 0, 4, 9, 2, 8, 2, 6, 3, 1, 1, 2, 3, 9, 0, 8, 5, 2, 1, 5, 0, 0, 8, 9, 7, 7, 2, 4, 5, 6, 9, 7, 6, 0, 1, 3, 1, 1, 0, 1, 4, 7, 8, 8, 1, 2, 0, 8, 4, 2, 4, 9, 0, 6, 9, 0, 6, 2, 2, 7, 4, 2, 5, 9, 0, 8, 0, 3, 8, 4, 0, 5, 2, 7, 4
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OFFSET
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0,1
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COMMENTS
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This constant is multiplied into the CORDIC algorithm to obtain the correct sine or cosine. See p. 647 of the fxtbook (below).
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LINKS
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FORMULA
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EXAMPLE
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0.60725293500888125616944675250492826311239085215008977245...
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PROG
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(PARI)
pent(z, n)= 1+sum(k=1, n, (-1)^k*(z^(k*(3*k-1)/2) + z^(k*(3*k+1)/2)));
/* == prod(n>=1, 1-z^n) via pentagonal number theorem */
N=30; u=0.25; K1=1/sqrt( 2 * pent(u^2, N)/pent(u, N) )
/* using prod(n>=1, 1+z^2) = prod(n>=1, 1-(z^2)^2)/prod(n>=1, 1-z^n) */
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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