id:A103055 - OEIS Search Results

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Numbers n such that 7*10^n + 3*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

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1, 3, 4, 5, 6, 9, 12, 31, 59, 69, 74, 287, 489, 592, 634, 1089, 1607, 3141, 5962, 6267, 9678, 11431, 12927 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (22*10^n-7)/3 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 733...331.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(22*10^n - 7)/3], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A088875 A022884 A105857 this_sequence A128995 A014101 A039035` `Adjacent sequences: A103052 A103053 A103054 this_sequence A103056 A103057 A103058`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005`
	EXTENSIONS	`More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008`

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Last modified February 9 11:24 EST 2010. Contains 172296 sequences.