A103074 - OEIS

This site is supported by donations to The OEIS Foundation.

A103074

Numbers n such that 8*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

2, 3, 5, 17, 47, 177, 8462 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (74*10^n-11)/9 is prime.`
	LINKS	`Table of n, a(n) for n=1..7.` `Makoto Kamada, Factorizations of 822...221.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(74*10^n - 11)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A211972 A076706 A019350 * A173236 A082979 A065952` `Adjacent sequences: A103071 A103072 A103073 * A103075 A103076 A103077`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v, Jan 19 2005`
	STATUS	`approved`

Content is available under The OEIS End-User License Agreement .

Last modified May 22 20:46 EDT 2013. Contains 225583 sequences.