A102990 - OEIS

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A102990

Numbers n such that 4*10^n + 3*R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

2, 3, 6, 11, 15, 26, 28, 51, 150, 182, 228, 407, 638, 3581, 4125, 4983, 5666, 15890, 27743 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (13*10^n+17)/3 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 433...339.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(13*10^n + 17)/3], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A090304 A005211 A076307 * A138520 A138519 A049794` `Adjacent sequences: A102987 A102988 A102989 * A102991 A102992 A102993`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`
	EXTENSIONS	`Addition of a(18)-a(19) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 10 2010`

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Last modified February 16 09:00 EST 2012. Contains 205904 sequences.