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A109694
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Decimal expansion of sum_n=1^inf 1/sigma_2(n).
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0
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1, 5, 3, 7, 8, 1, 2, 8, 9, 1, 8
(list; constant; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| product_p sum_k=0^inf 1/sigma_2(p^k)
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EXAMPLE
| 1.5378128918...
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PROG
| (PARI) N=1000000000 prodeuler(p=2, N, sum(k=1, 200/log(p), if(k==1, 1., 1./((p^(2*k)-1)/(p^2-1))))
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CROSSREFS
| Cf. sigma_2 A001157.
Sequence in context: A110265 A021190 A186905 * A135765 A030669 A030679
Adjacent sequences: A109691 A109692 A109693 * A109695 A109696 A109697
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KEYWORD
| cons,more,nonn
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AUTHOR
| Frank Adams-Watters (FrankTAW(AT)netscape.net), Aug 07 2005
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