A091189 - OEIS

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A091189

Primes of the form 20*R_n + 1, where R_n is the repunit (A002275) of length n.

2221, 222222222222222221, 2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222221 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Primes of the form 222...221.` `The number of 2's in each term is given by the corresponding term of A056660 and so the first term too large to include above is 222...2221 (with 120 2's).`
	CROSSREFS	`Cf. A056660 (corresponding n).` `Cf. A051200, A004022, A093176, A093177, A089346.` `Sequence in context: A183831 A092992 A166580 * A046443 A043500 A118116` `Adjacent sequences: A091186 A091187 A091188 * A091190 A091191 A091192`
	KEYWORD	`bref,nonn`
	AUTHOR	`Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 22 2004`

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Last modified February 17 06:27 EST 2012. Contains 205998 sequences.