id:A074717 - OEIS Search Results

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Least k such that floor(2^n/k) is prime.

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1, 2, 3, 3, 6, 9, 11, 11, 7, 9, 5, 10, 19, 11, 5, 10, 9, 11, 22, 35, 39, 9, 5, 10, 20, 27, 11, 19, 9, 18, 36, 25, 29, 27, 5, 10, 20, 40, 61, 13, 21, 42, 29, 27, 39, 9, 17, 29, 58, 49, 27, 25, 50, 11, 22, 44, 39, 11, 22, 44, 29, 58, 116, 53, 19, 38, 76, 152, 237, 139, 5, 10, 20 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`There is probably a constant c such that sum(i=1, n, a(i)) is asymptotic to c*n^2 ( 0<c<1/2)`
	PROGRAM	`(PARI) a(n)=if(n<0, 0, k=1; while(isprime(floor(2^n/k)) == 0, k++); k)`
	CROSSREFS	`Sequence in context: A020878 A027100 A060840 this_sequence A129068 A079888 A059191` `Adjacent sequences: A074714 A074715 A074716 this_sequence A074718 A074719 A074720`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 04 2002`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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