A033809 - OEIS

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A033809

Smallest m>0 such that (2n-1)2^m+1 is prime, or -1 if no such value exists.

1, 1, 1, 2, 1, 1, 2, 1, 3, 6, 1, 1, 2, 2, 1, 8, 1, 1, 2, 1, 1, 2, 2, 583, 2, 1, 1, 4, 2, 5, 4, 1, 1, 2, 1, 3, 2, 1, 3, 2, 1, 1, 4, 2, 1, 8, 2, 1, 2, 1, 3, 16, 1, 3, 6, 1, 1, 2, 3, 1, 8, 6, 1, 2, 3, 1, 4, 1, 3, 2, 1, 53, 6, 8, 3, 4, 1, 1, 8, 6, 3, 2, 1, 7, 2, 8, 1, 2, 2, 1, 4, 1, 3, 6, 1, 1, 2, 4, 15, 2 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,4`
	COMMENTS	`There exist odd integers 2k-1 such that (2k-1)2^n+1 is always composite.`
	REFERENCES	`Ribenboim, P. The New Book of Prime Number Records. New York: Springer-Verlag, pp. 357-359, 1996.`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..1000`
	CROSSREFS	`Cf. A046067 (except for initial term a(1) identical to this sequence), A046068, A046069, A046070.` `Cf. A040076` `Sequence in context: A128807 A309035 A071628 * A046067 A342416 A305531` `Adjacent sequences: A033806 A033807 A033808 * A033810 A033811 A033812`
	KEYWORD	`sign`
	AUTHOR	`Eric W. Weisstein`
	STATUS	`approved`

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Last modified January 2 00:37 EST 2023. Contains 359186 sequences. (Running on oeis4.)