id:A102981 - OEIS Search Results

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Numbers n such that 4*10^n + R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

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1, 4, 5, 13, 31, 55, 58, 59, 61, 79, 91, 103, 121, 196, 229, 9439 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (37*10^n+17)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 411...113.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(37*10^n + 17)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A147001 A140683 A071341 this_sequence A029663 A082312 A091311` `Adjacent sequences: A102978 A102979 A102980 this_sequence A102982 A102983 A102984`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 21 2004`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.