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Search: id:A049040
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| A049040 |
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Number of Sophie Germain primes <= Prime[ 10^n ]. |
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2
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OFFSET
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1,1
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COMMENT
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Sophie Germain primes are primes p such that 2p+1 is also prime.
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LINKS
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Index entries for sequences related to numbers of primes in various ranges
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EXAMPLE
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The first 10 primes are 2,3,5,7,11,13,17,23,29 and 31. 6 of these are Sophie Germain primes, namely: 2,3,5,11,23 and 29.
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MATHEMATICA
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<< NumberTheory`NumberTheoryFunctions`; cnt = 0; currentPrime = 1; For[ i = 1, i == i, i ++, currentPrime = NextPrime[ currentPrime ]; If[ PrimeQ[ 2*currentPrime + 1 ], cnt++ ]; If[ IntegerQ[ Log[ 10, i ] ], Print[ cnt ] ]; ]
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CROSSREFS
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Sequence in context: A046233 A140231 A100308 this_sequence A053946 A027283 A009639
Adjacent sequences: A049037 A049038 A049039 this_sequence A049041 A049042 A049043
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KEYWORD
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nonn
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AUTHOR
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Dennis S. Kluk (mathemagician(AT)ameritech.net)
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EXTENSIONS
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More terms from Alex Healy (ahealy(AT)fas.harvard.edu), Mar 19 2001
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