id:A102998 - OEIS Search Results

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Numbers n such that 4*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

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1, 4, 10, 12, 13, 40, 76, 123, 501, 648, 3541, 4002, 4228, 5271, 7432 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (44*10^n-53)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 488...883.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(44*10^n - 53)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A090070 A078005 A092428 this_sequence A071179 A155475 A023693` `Adjacent sequences: A102995 A102996 A102997 this_sequence A102999 A103000 A103001`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`

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Last modified December 11 12:57 EST 2009. Contains 170656 sequences.