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Search: id:A091189
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A091189 Primes of the form 20*R_n + 1, where R_n is the repunit (A002275) of length n. +0
2
2221, 222222222222222221, 22222222222222222222222222222222222222222222222222222222222222222222222222222222\ 22222222222222222221 (list; graph; listen)
OFFSET

1,1

COMMENT

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: A138079 A092992 A166580 this_sequence A046443 A043500 A118116

Adjacent sequences: A091186 A091187 A091188 this_sequence A091190 A091191 A091192

KEYWORD

bref,nonn

AUTHOR

Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 22 2004

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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