id:A078687 - OEIS Search Results

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Number of x>=0 such that prime(n)-2^x is prime.

+0
5

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

	OFFSET	`1,4`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..1000`
	FORMULA	`a(A049084(A065381(n)))=0, a(A049084(A065380(n)))=1; A118953(n)<=a(n); a(n)=A109925(A000040(n)). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 07 2006`
	EXAMPLE	`prime(17)=59 and only 59-2^3 = 53 is prime hence a(17)=1`
	PROGRAM	`(PARI) a(n)=sum(i=0, floor(log(prime(n))/log(2)), if(isprime(prime(n)-2^i), 1, 0))`
	CROSSREFS	`Sequence in context: A083898 A078314 A068322 this_sequence A133138 A037180 A091222` `Adjacent sequences: A078684 A078685 A078686 this_sequence A078688 A078689 A078690`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Dec 17 2002`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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