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A156876
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Number of numbers <= n that are safe primes or Sophie Germain primes.
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6
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0, 1, 2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| a(n) = A156874(n)+A156875(n)-A156877(n) = A000720(n)-A156878(n).
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 1..10000
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EXAMPLE
| a(120)=#{2,3,5,7,11,23,29,41,47,53,59,83,89,107,113}=15.
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CROSSREFS
| A156658, A005384, A005385, A000720.
Sequence in context: A157792 A171896 A094235 * A137397 A062571 A102515
Adjacent sequences: A156873 A156874 A156875 * A156877 A156878 A156879
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 18 2009
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