A102948 - OEIS

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A102948

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

1, 3, 7, 13, 24, 30, 48, 52, 163, 175, 219, 228, 261, 754, 951, 1344, 1573, 3294, 3523, 14161 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (19*10^n+17)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 211...113.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(19*10^n + 17)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A147380 A146606 A101302 * A061263 A156209 A076276` `Adjacent sequences: A102945 A102946 A102947 * A102949 A102950 A102951`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004`
	EXTENSIONS	`Addition of a(20) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 09 2010`

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Last modified February 16 21:04 EST 2012. Contains 205969 sequences.