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A156878 Number of primes <= n that are neither safe primes and nor Sophie Germain primes. 5
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,17
LINKS
FORMULA
a(n) = A000720(n) - A156876(n).
EXAMPLE
a(120) = #{13,17,19,31,37,43,61,67,71,73,79,97,10,103,109} = 15.
CROSSREFS
Sequence in context: A010096 A230864 A063510 * A214454 A140474 A091195
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 18 2009
STATUS
approved

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)