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A109693
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Decimal expansion of sum_n=1^inf 1/sigma(n)^2.
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0
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1, 3, 0, 6, 4, 5, 6, 5, 1, 2, 0
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..11.
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FORMULA
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product_p sum_k=0^inf 1/sigma(p^k)^2
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EXAMPLE
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1.3064565120...
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PROG
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(PARI) N=1000000000 prodeuler(p=2, N, sum(k=1, 200/log(p), if(k==1, 1., 1./((p^k-1)/(p-1))^2)))*(1+1/N/log(N))
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CROSSREFS
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Cf. Sigma function A000203.
Sequence in context: A088162 A133170 A062542 * A188858 A199610 A004606
Adjacent sequences: A109690 A109691 A109692 * A109694 A109695 A109696
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KEYWORD
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cons,more,nonn
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AUTHOR
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Franklin T. Adams-Watters, Aug 07 2005
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STATUS
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approved
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