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A110788 Copies of 7 and 1 alternately such that every partial concatenation is a prime. 10
7, 1, 77, 1111, 77777, 1111111111, 77777777777777777777777, 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
7, 71, 7177, 71771111, ... are all prime.
CROSSREFS
Sequence in context: A281620 A321187 A221367 * A100254 A119935 A027447
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Aug 13 2005
EXTENSIONS
More terms from Joshua Zucker, Jan 11 2006
STATUS
approved

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Last modified March 18 22:47 EDT 2024. Contains 370951 sequences. (Running on oeis4.)