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

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]

Links

Table of n, a(n) for n=1..4.

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. A048890, A055558.

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

Sequence in context: A065582 A241021 A055558 * A113596 A155670 A085770

Adjacent sequences: A160449 A160450 A160451 * A160453 A160454 A160455

Keyword

more,nonn,base

Author

Lekraj Beedassy, May 14 2009

Status

approved