id:A156877 - OEIS Search Results

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Number of numbers <= n that are safe primes and also Sophie Germain primes.

+0
5

0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4 (list; graph; listen)

	OFFSET	`1,11`
	COMMENT	`a(n) = A156874(n) + A156875(n) - A156876(n);` `a(n) = SUM(A156659(k)*A156660(k): 1<=k<=n).`
	LINKS	`R. Zumkeller, Table of n, a(n) for n = 1..10000`
	EXAMPLE	`a(120) = #{5, 11, 23, 83} = 4.`
	CROSSREFS	`A059455, A005384, A005385, A000720.` `Sequence in context: A057467 A074594 A001069 this_sequence A110591 A105209 A095861` `Adjacent sequences: A156874 A156875 A156876 this_sequence A156878 A156879 A156880`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 18 2009`

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Last modified December 17 13:29 EST 2009. Contains 170826 sequences.

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