id:A102990 - OEIS Search Results

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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.

+0
2

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

	OFFSET	`1,1`
	COMMENT	`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 this_sequence A138520 A138519 A049794` `Adjacent sequences: A102987 A102988 A102989 this_sequence A102991 A102992 A102993`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.