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A110780 Copies of 1 and 9 alternately such that every partial concatenation is a prime. 14
11, 99999, 111111111, 9999999999, 11111111111111111111111111111111111111, 99999999999999999999999999999999999999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

11,1199999,1199999111111111,... are all prime.

CROSSREFS

Cf. A110774, A110775, A110776, A110777, A110778, A110781.

Sequence in context: A102367 A055322 A165934 * A087395 A199169 A145571

Adjacent sequences:  A110777 A110778 A110779 * A110781 A110782 A110783

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Aug 12 2005

EXTENSIONS

More terms from Joshua Zucker, Jan 11 2006

The next term has more than 800 1's and is too large to include.

STATUS

approved

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Last modified February 25 22:55 EST 2020. Contains 332270 sequences. (Running on oeis4.)