id:A057024 - OEIS Search Results

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Largest odd factor of (n-th prime+1); k when n-th prime is written as k*2^m-1 [with k odd].

+0
3

3, 1, 3, 1, 3, 7, 9, 5, 3, 15, 1, 19, 21, 11, 3, 27, 15, 31, 17, 9, 37, 5, 21, 45, 49, 51, 13, 27, 55, 57, 1, 33, 69, 35, 75, 19, 79, 41, 21, 87, 45, 91, 3, 97, 99, 25, 53, 7, 57, 115, 117, 15, 121, 63, 129, 33, 135, 17, 139, 141, 71, 147, 77, 39, 157, 159, 83, 169, 87 (list; graph; listen)

	OFFSET	`1,1`
	LINKS	`Index entries for sequences of n such that k2^n-1 (or k2^n+1) is prime`
	FORMULA	`a(n) =A000265(A000040(n)+1)) =A000265(A028815(n)) =(A000040(n)+1)/A007814(A000040(n)+1) =A028815(n)/A023512(n)`
	EXAMPLE	`a(5)=3 because 5th prime is 11 and 11=3*2^2-1`
	CROSSREFS	`Cf. A057023.` `Sequence in context: A046933 A023511 A035628 this_sequence A023892 A085417 A095660` `Adjacent sequences: A057021 A057022 A057023 this_sequence A057025 A057026 A057027`
	KEYWORD	`nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), Jul 24 2000`

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

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