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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A160452 Invertible primes of the form 1 followed by a string of 9's.

Original entry on oeis.org

19, 199, 1999, 1999999999999999999999999999
Offset: 1

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Author

Lekraj Beedassy, May 14 2009

Keywords

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]

Examples

			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. A048890, A055558.
Cf. A092571, A002957. [From Dmitry Kamenetsky, May 22 2009]
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