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A160452
Invertible primes of the form 1 followed by a string of 9's.
0
19, 199, 1999, 1999999999999999999999999999
OFFSET
1,1
COMMENTS
These are values in A055558 whose rotation by 180 degrees occurs in A092571. I have checked all the numbers that correspond to entries in A002957 and can confirm that the next term in this sequence, if it exists, is greater than 2*10^55347-1. [From Dmitry Kamenetsky, May 22 2009]
EXAMPLE
1999, for instance, is a prime which rotated upside down through 180 degrees becomes the prime 6661. Hence 1999 is in the sequence.
CROSSREFS
Cf. A092571, A002957. [From Dmitry Kamenetsky, May 22 2009]
Sequence in context: A065582 A241021 A055558 * A113596 A155670 A085770
KEYWORD
more,nonn,base
AUTHOR
Lekraj Beedassy, May 14 2009
STATUS
approved