id:A102992 - OEIS Search Results

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Numbers n such that 4*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

+0
4

1, 2, 4, 5, 13, 22, 25, 28, 38, 67, 142, 284, 295, 380, 397, 1217, 1640, 2885, 3286, 7735 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (41*10^n+13)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 455...557.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(41*10^n + 13)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Adjacent sequences: A102989 A102990 A102991 this_sequence A102993 A102994 A102995` `Sequence in context: A139485 A079407 A078652 this_sequence A136563 A127077 A104549`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`

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Last modified May 16 01:24 EDT 2008. Contains 139630 sequences.